I'm a pretty heavy GoG customer and I disagree with a lot of this premise. Most games aren't getting updates past a year or two after their release, and the ones that are aren't DRM-free. And even if they weren't, I'd rather be able to play an older revision of a game I own than not own it at all.

Your Steam games run on Linux run due to Valve's (truly excellent) work on their compatibility layer. However, that work is not exclusive to Steam. I can play my DRM-free GoG copies of big budget Windows games just fine on Linux. There's an extra step you have to invoke, but they still run superbly. Supporting DRM-free is the best we have in an increasingly hostile customer market.