StingingVelvet: GG have said the publishers demand their installers work the way they do. It stands to reason that if publishers knew those installers had an easy work-around they might be upset and ask for the loophole to be closed.
I'd love to know who these "publishers" are, because if they really exist, I would make sure they wouldn't get any of my money nor that of my friends anymore. But I doubt they'd speak up about it because it would make them look really foolish, as the whole thing doesn't make any sense at all. I've only ever seen "DRM-free" or some 3rd party DRM on GG's game pages (I know that GG sometimes adds SecuRom on demand), but I have yet to see an indication that "this game's installer is protected by GG's client". Besides, I call that fraud to advertise games as DRM-free when they really rely on the service's online activation client.
If a publisher would say something like what you mentioned above about Steam, I could understand, but at least Steam doesn't officially pretend to sell DRM-free games on their webpages. And contrary to Steamworks the GG client doesn't come with any advantages for the users whatsoever.
Anyway, I agree that one could have found the relevant information elsewhere, without creating another thread.