To answer that simply and plainly, Omegacloud, it's because of the rampant piracy on the PC. Don't forget, Steam is at its heart, a DRM system. It has some nice bells and whistles attached to it in the form of content delivery and such, but as we all know, it has its disadvantages as well.
The piracy rate on consoles is totally insignificant compared to the rate on the PC for obvious reasons.
Stannie
Skyrim was out with a crack a week before 11/11/11 on even public torrent trackers such as Arrghh!

So either the intention was a failure or the intention is something different and the piracy is an excuse. DRM
NEVER worked for not even one game at all...ever. The only thing I can recall that was not only smart and effective(can't remember the game) was that if you had a pirated version the first boss was invulnerable and unkillable ....now that is how you deal with piracy as opposed to pre supposing everyone is a potential pirate.
I also fully endorse this statement:
No, if you set Steam to not update the game automatically, it will update anyway the next time you try to start the game. And I don't want to have to keep going in offline mode every time I want to play. And knowing Steam's offline mode, I'd be lucky if I could even start the damn thing without going online to update. And what if my power shuts off and interenet cuts out while Steam is running? Guess what, IT IS THEN IMPOSSIBLE TO SIGN INTO STEAM WITHOUT GOING ONLINE AGAIN FIRST. THAT MEANS I CAN'T EVEN PLAY THIS GAME I BOUGHT. And I can't keep Steam offline forever, because like many people, I have multiplayer games which require Steam to be online.
And how about them tying the HD texture pack to your account, so you couldn't uninstall those gigs of data off your harddrive without asking the Steam Support Overlords first?
There's quite a few reasons to be angry with Steam. It shouldn't be this way for a single player game.
-KGN 004
Inc mod telling us to go to a steam forum in regards to their software that requires the aforementioned DRM btw....