This.
At the crux of my resistance to Steam, or any service like it, is the fact that someone can take my games from me. If I pay my hard earned money for a game I want to actually have the game, not just the opportunity to play when the conditions are right. And before someone raises the "you don't own the game you just bought a revokable license to play" argument, yes when I install a game I agree to abide by the EULA. However Steam can lockout my account, thus effectively revoking all game licenses, for reasons not listed in any games EULA. If someone hacks my account, or steals my credit cards, or some piece of software on my computer conflicts with the Steam anti-cheat detection; then I lose the ability to legally play the games I purchased. I refuse to pay actual money for something I will never actually own.