Steam's DRM is completely different from all other DRM's. The way Steam works by controlling distributing games is not restricting. It is rather enabling. If my disc blows up, cratches or by any other means renders it unreadable then I can still download my game and play it.
I don't need the disc. I don't need the CD key. There are not evil rootkits. It is not restricting me at all.
In fact it is enabling me to download and play my games everywhere. I can download it so much (if I wanted to) that Valve's bandwith costs make them lose their profit from me buying once and play everywhere.; It can even make them lose money (and they probably already did, lol

).
They have, and tested it, an exit trategy. Valve's DRM doesn't make me play the game less, or not at all. It lets me play games more. Even when they are bankrupt!
Now onto the Digital
Restriction Management that is everywhere else: I am highly against that! And so unless Primal Carnage goes Steam and doesn't implement its own copy protection whatsoever I will not buy it. I will not even think about buying it for a second!
It's either no copy protection at all and laying the protection in Valve's hand or a massive no go!
And that is why we are all against DRM in the first place, because it restricts. Steam's DRM enables by decrypting games that do not have any copy protection themselves. The only reason these games are not playable on their own is because they are encrypted. They do not require Steam at all. And FWIW; you can download them all decrypted and you do not need a crack for them.
I bought all my Valve games for a reason and only downloaded Half-Life 2 because I didn't know about the backup features and the official unlock forevah patch that Valve tested inhouse.