SimonG: So you judge the quality of games based on personal availability....
There's only so much resources I can spend toward adjudicating the quality of games and choosing the "best" one. Which game is better, Deponia or Satinavs Ketten?
How should I know? Well, I have Deponia on a download service I (arbitrarily) like more, so it makes sense to play that.
Why not both? I can't play two games at the same time. And once I'm done with a game, it's again "hundreds of appealing games that I have on the arbitrarily attractive service" vs "Satinavs Ketten, Emerald City Confidential, and thousands of potentially good games that I know nothing about up to and including their titles". A game is not objectively better because it's on a more likeable service - it's just, for me, playing GOG games is more efficient. If something actually top-priority gets a Steam-only release, of course I will buy it there.
But if you made an effort to appreciate competing services, maybe you'd have even more fun! Maybe. However, optimizing fun at the cost of fun, forcing yourself to like something, is generally a loser's gambit. I tried Steam. I didn't like Steam (before I was aware of DRM politics, I didn't like the mandatory client and hated achievements). I won't pass up a must-play, there's just no must-plays.