As mentioned on here, Steam itself is a form of DRM. When you buy a game from Steam, you don't really "own" the game. If you can't sell the game, can you really "own" it? No. In principle, I feel that what Valve is doing is evil. It's just less evil than what other Pro-DRM companies are doing. That's why gamers give them a free pass. But they shouldn't get a free pass. Just because Ubisoft, EA, etc. are more evil, doesn't mean that Valve is good. You just get less evil with Valve.
I don't see how Steam is a net benefit for consumers. You can install your games on as many computers as you like? You can do the same with DRM-free games. And you can resell those if you want.
You have achievements? So what? Xbox 360 does and you can sell your retail Xbox 360 games.
You have friends list? Ditto.
You have free multiplayer servers? Battle.net has that too. And so as long as you aren't dealing with a douchebag seller who keeps using the serial key after selling the game, I'm pretty sure you can buy a used copy of Diablo, Starcraft or Warcraft without a hitch. It's risky to buy those games second-hand but at least you can provided that the seller is honest (this is what feedback ratings on ebay are for).
You don't need to put the disc inside the computer while you play? DRM-free games allow that too (disc check is a form of DRM btw and yes there are retail games out there still that don't even require a disc check). And you can resell those.
Steam has some killer sales at times. I'll give it that. But I don't "get" what's so great about Steam overall. Gamers are doing a disservice to themselves for talking up a company that is committed towards destroying true ownership and consumer rights (first-sale doctrine).







