A feature which is heavily requested ( top wish on the community site feature wishlist) and intensively discussed by the community (1 and many more threads), is GOG support for linux (the ecosystem, not the kernel).

So, why is GOG not offering this? Is there a good reason for missing this chance and market?

GOG statements on linux support
http://www.gog.com/forum/general/linux_support_on_gog/post14
[...]let's just look at what *I* can think of that makes Linux release a very difficult proposition:
1: Testing. What distros do we support? There are 10 "fairly common" ones [...]. Hardware? What level of updates? [...] Managing testing across the 3 OSes we support is tough and requires a lot of time, effort, and money. How much more complex will 10 more OSes make it?
2. Support. [...] LInux is famous as the hacker's OS--that is to say, the OS of people who like to do odd things with their hardware. If someone contacts Support because he can't get his copy of Fallout running on his Raspberry Pi with a video out that's connected to a six-panel e-ink display and he wants his money back, well, that puts us in a bad spot.
3. Maintanence. Across those 10 common distros, how often does one of them update? Quarterly? Monthly? I don't know, but the answer is certainly "often". What do we do if slackware updates and breaks the functionality of a glide wrapper that we're using for all of our games? [...]I'm sure some businesses may even consider that a successful business model--but that's not really the GOG way of doing business. ;)
[...]. Linux is, what, 1% of the market for desktop computers? That's a lot of work for a very small audience. It's still quite possible that, after evaluation, the answer will still be, "No, sorry, This will cost us more money than it makes."

"[...] PCG: And Linux? TL: Linux gaming is also something we’d love to do, but we haven’t made any announcements about it yet. We’ve been looking at it. I’ve been making public statements for a while that there are technical hurdles. Steam’s approach is to say, “Here’s our distro, we support this distro. Have another distro? Sorry.” That’s not how GOG does things, we’re more free-range gaming. So we’re looking at how to deliver the GOG experience on— we can’t say every computer, because you can of course hook up an E Ink display with 2-color CGA as your monitor, use Lynx as your web browser, and run some weird Debian distro that you’ve custom modded to do just what you want and then say, “How come I can’t play your games? [...]”

(rough) Summary: "GOG: We would like to support the linux ecosystem... but we don't know how to do it in (technical and economical) feasible way."

Situation/History
Is gog.com right? Is the task of supporting the linux ecosystem too demanding and complicated? Or, are they just "whiners" ? There is also the HIB, the steam linux client project etc...
Maybe, maybe not... but there seems to be a long stream and history of criticsm on deployment, development and support mechanisms for third party applications on linux. By people who should know, people involved:

2006: Benjamin Smedberg (Mozilla) Is Ubuntu an Operating System? "The final (and perhaps most pernicious) problem when thinking about redistributable software is the ongoing binary incompatibility between various Linux distributions and between versions of the same Linux distribution."
2006: Ian Murdock (Debian Founder/)</span> [url=http://ianmurdock.com/linux/software-installation-on-linux-today-it-sucks-part-1/]Software installation on Linux: Today, it sucks (part 1) "And, no, moving everything into the distribution is not a very good option. Remember that one of the key tenets of open source is decentralization, so if the only solution is to centralize everything, there’s something fundamentally wrong with this picture."
2007: Mike Hearn ()</span> [url=http://web.archive.org/web/20080405004634/http://www.linux.com/articles/60124]Autopackage struggling to gain acceptance "The whole idea of packaging/installation is bogus and leftover from the times when software was distributed on floppy disks," Hearn claims. "The web 'instant activation' model is better but requires advances in client-side platforms first around streaming and security."
2009: Tony Mobily (FS Magazine) 2009: software installation in GNU/Linux is still broken -- and a path to fixing it "Every GNU/Linux distribution at the moment (including Ubuntu) confuses system software with end user software, whereas they are two very different beasts which should be treated very, very differently.“
2010: Dave Burke (Osmos) Porting Osmos to Linux: A Post-Mortem (part 2/3) "Didn’t Love: Packaging the Game. It took days of effort to create the binary packages for Osmos [...] How should an app be packaged in Linux? [...]There are no standards or clear answers to any of these questions. There’s no documentation for this stuff! Asking on the forums will typically net you a spectrum of answers with no consensus answer and lots of little side arguments.[...]“
2010: Matthew Paul Thomas (Ubuntu) Upgrading packaged Ubuntu application unreasonably involves upgrading entire OS "It is easier to upgrade to the newest stable versions of most applications -- even open source applications -- on a proprietary operating system than it is on Ubuntu."
2012: Ingo Molnar (Kernel developer) Technology: What ails the Linux desktop? Part I. "[...]many OSS developers don't realize what a deep hole we are in. The desktop Linux suckage we are seeing today - on basically all the major Linux distributions - are the final symptoms of mistakes made 10-20 years ago - the death cries of a platform."
2012: Miguel de Icaza (gnome founder): What Killed the Linux Desktop "But we missed the big picture. We alienated every third party developer in the process."

What to do?
I think gog has good reasons to evaluate the support of the linux ecosystem very cautious... maybe the linux community should do the first step and remove some obstacles.

First step should be the acceptance that the fragmentation of the linux distros is a hinderance, that missing stable API/ABIs are a problem and that the deployment via centralized repros & packagemanagmet is not a universal solution. Third party developers and distributors (like GOG) demand a simple distro independent way for app development, deployment and support (in binary form) ... which works for the whole linux ecosystem for a reasonable amount of time, with a reasonable effort.

Sadly, 2 major chances to improve this situation were missed: 2005 the project by Mike Hearn was [url=http://web.archive.org/web/20080405004634/http://www.linux.com/articles/60124]overwhelmed by LSB was also not succesful enough.

But luckily, the endless variety of the linux ecosystem hides several alternatives which could be a start:
[url=http://portablelinuxapps.org/ ]portablelinuxapps.org [/url] "Distribution agnostic portable software packages"
zero-install.sourceforge.net "Zero Install is a decentralised cross-distribution software installation system."
http://www.pgbovine.net/cde.html "CDE: Automatically create portable Linux applications"

So, what do you think, what can be done and what must be done to help GOG in supporting the linux ecosystem?

(and if not enough can be done... are there alternatives ?)

The post by TheEnigmaticT that you quote also includes him listing FreeBSD as a Linux distro. I shudder to think that GOG is making their Linux decisions based on such abject ignorance.

Hopefully, that was just a brainfart on his part. To be fair most likely he went on distrowatch and picked out the OS on their top 10 without actually reading it

Except that you're forgetting one small aspect of this: neither HiB nor Steam are the ones who provide support for the games sold there, but the actual developers.

In GOG's case they are the ones who provide actual support for the product, so choosing those places as an example isn't really a good idea. Why? While technically not a Linux distribution it has the exact same problems as they do, namely poor hardware support and small consumer marketshare though you can arguably say that it avoids the fragmentation that Linux based distros face.

That's just arguing for arguments sake.

Way to miss the forest for the trees.

I've been saying this for years to people when we've discussed about Linux distros. There's too much fragmentation. While OSS is very good thing for innovation, it can be a bad thing for coherency.

If Linux wants a bigger share as a desktop OS there should be "the one" distro, that would be selected as the official for all purpose distro. This distro could be then used to be the plow horse, that could get other parites involved. There also should be more undestandmet for proprierity driver suppot, as in some cases it feels there's only one way in Linux, which can intimidate the potentially interested hardware manufacturers away.

Sadly, I feel, in some cases the OSS communities are their own biggest enemy at the moment.

That would require more than two people to come to an agreement, which is impossibru :-P I think Ubuntu's slowly getting there in the general counsciousness tho.

I'm starting to come around to the notion that GOG should be thinking a lot harder about Linux support, even if it's just for their indie titles that already have working Linux ports out there. The people at GOG should be savvy enough to understand and recognize that unlike most mainstream computer users, Linux users are more than able and willing to put in the necessary effort to get their games to work across distros.

While I can understand TET's statement that they do not want to restrict themselves to just one part of Linux (something he also said to me in my interview with him for Inside Mac Games), I'd wager than offering Linux binaries as .RPM and .DEB packages should cast a wide-enough net in terms of general Linux compatibility; though I honestly don't know how difficult it would be for them to effectively pull off.

The other important thing to remember, especially for their classic releases, is the legal issue. It took them about a year to get the legal green light for their Mac releases, so taking that as a cue, I'd imagine that it would take at least that long to get a credible lineup of Linux launch titles ready.

The forest is GOG's seeming irrational ill will toward Linux to the point of them not even wanting to distribute ALREADY existing Linux installers/binaries as unsupported extras despite willing to do the exact same thing with for example The Lady, The Mage, and The Knight tech demo distributed along side Beyond Divinity. This results in the GOG version of some games being inferior, for example in cases where games support Steam for Linux and Steamplay.

Meaning you can buy them on Steam and get both Windows and Linux(and often Mac as well) binaries or you can get them on GoG and get Windows (and sometimes Mac) binaries only. Obviously GOG has DRM free versions but sometimes Steam has that as well and indie developers often offer DRM free versions on their websites. Sometimes Linux binaries are offered on developer websites as free extras so you could buy the GOG version and download the Linux binaries from there. But sometimes you would have to buy an extra non-GOG version of the game in order to get it for Linux. Why then buy the GOG version at all?

The point he was trying to make is that the fragmentation issue is real, and a mental gaffe like the one you've latched onto doesn't make it go away. I mentioned putting up .DEB and .RPM packages as a potential solution, but I know there are other package managers out there, and a lot of users would likely cry foul for not having their preferred package manager not being supported.

People calling for GOG to throw up Linux binaries seem to imply that said binaries will work universally on all systems across all distros and hardware configurations; or at least, that we can assume the same level of hardware/OS homogeneity that we can for Windows or OS X. Is that actually a valid assumption to make across Linux as a whole?

I also don't buy the argument around the Beyond Divinity tech demo. Simply because...it's a tech demo. It's not a full game, nor is it a binary to get a full game working on a previously unsupported OS. If they did do something like put up the original Mac OS 9 releases of games like Shadow Warrior and Duke Nukem 3D up as extras, then yes, I'd fully agree with you. But they haven't.

And finally, it's really time to stop assuming that GOG has some kind of anti-Linux agenda or that they somehow hate Linux users. There's absolutely nothing at all from them, officially, unofficially, explicitly, or implicitly, to suggest that they're not supporting Linux out of petty spite. They made that decision because in terms of their own business calculus, the gains aren't worth the potential risks. Acting like GOG is somehow engaging in some anti-Linux conspiracy isn't going to help them change their minds.

If I got a pony, neither it nor I would have much fun in my apartment, so I won't get a pony. Ergo, I have irrational ill will toward ponies.

Damn it Linux, get your shit straight!

What the Beyond Divinity example shows is a willingness to put up unsupported extras. What those extras actually are should be irrelevant.

As far as the diversity/fragmentation issue goes:

1. Others have dealt with it just fine in various ways.
2. It is a only ever an issue if you want to put up official support for Linux, merely uploading some unsupported binaries so that the GOG version is not inferior to other versions doesn't require addressing the issue at all. It is just doing Linux gamers a small favor so that they can buy the games in question from GOG just as easily as from say Steam or the developers them selves. After all the binaries are exactly the same as they would have gotten from those places and so work just as well or just as badly. But it would ensure that the GOG version would cease being directly inferior in any way.
3. In cases where developers already have ported the games, they have already faced this issues and have dealt with them in some way.
4. While the issue of fragmentation is very real, it is also FUD to a certain extent. There are plenty of packages, applications and games of all kinds that work just fine across a wide variety of distributions.
5. If GOG wanted to they could limit their support(I must again emphasize that I am not asking for official support only unsupported Linux binaries, but it would be a huge bonus!) to a single disto, such as Ubuntu. What would be problem with this? They could just look at different distros and different OSes and say that they have added support for a new OS namely Ubuntu Linux.
6. While the problem may be bigger on Linux, the Windows world isn't without fragmentation, currently GOG is supporting Windows XP, Vista, 7 & 8 to different extents.

And just a day or two a go a particular person called it "spyware". -_-