Well, that (edit: the "Steam or nothing" point, I was ninjaed) is not entirely true, it was not about "Steam or nothing". When steam was still growing, there were alternatives, and I am not talking about retail versions right now.
Remember MC Games? I still got the offline installers of some games I bought from them. even now that they are long gone. And there were also others. I had games on GFWL as well (sadly it was crap).

I too chose Steam. Sure, first it was outrageous, that Half-Life 2 (I had the big black box with all Half-Life games in it) required it and of course the first thing I did was to crack it. Sometimes later I would register it anyway. At that point I thought "what's the difference?". Online registration had been a thing for some time by then, just the launcher was new.
I still have the big fat Space Marine Package with the heavy book in it. It had to be registered at Steam of course. A Steam edition for SWG with an exclusive item? I bought it, even if I still played the normal version.

You were not forced to use Steam, but it had advantages, it was easy to get keys (computer magazines). Valve did a good job pushing the agenda. Also it was cool that you could gift items or spare keys to friends, because almost everyone was using Steam.

What got me to abandon Steam however, was how that whole community bullsh** was pushed, how competition was encouraged (something I hated in WOW, that's why I prefered SWG, it was more of a 'together' than 'against') and most of all that everything was tracked, tracking can't be deactivated. So I started cracking my Steam games and realized that this was not the way to go.
I am not strictly against that, I play games on Ubisoft and Origin as well and these track as well, but the whole thing how this is brought to the community is something else on Steam. That's a whole different level.

What brought me to GOG was that they had some old adventures (Gabriel Knight and Tex Murphy) and that they would offer offline installers that would not need a client that would track. By now I replaced a big portion of my Steam library with GOG and sometimes Epic versions.
For some games I do use Galaxy, even if I am not much of a achievement hunter I like to see them for some specific games in my library, GOG was kind enough to offer us a switch to deactivate time tracking. I don't know if Galaxy collects hardware informations like Steam does, and frankly I don't want to know.

The downsides of course are not knowing if or when a game will come here, having no guarantee that the game will get updates and of course the price of freedom: Cut down games that miss part of the content. And if they are not cut down but offer that content when being logged in to Galaxy, it's the people who whine about DRM.


edit: and don't say too loud that Steam only has a 'few' drm free games or someone will jump in and tell you that most games are DRM free and then mention, that you have to count in indies of course. That and often people don't think it's drm if you can bypass it using a text file or a cracked dll. It's still a licence check, the game was just cracked. Only if the game is able to run without the steam dll (or galaxy dll) it can be considered DRM free.