I fully agree that violent games should be rated and access to them restricted to those of a suitable age. I don't think kids should be playing violent games, as they de-sensitise them and give them an inaccurate picture of the world.
However, the reasoning is all wrong. Games do not teach people to stalk, maim, torture and kill. Sure, a lot of them involve killing, some involve stalking... but torture, maiming? Show me one game that involves torturing someone (actually Contract J.A.C.K. has a torture sequence but it's totally removed from reality) and teaches you how to torture someone...
As has been said earlier, games don't teach you anything of value in real word use. Shooting a gun in a game is nothing like shooting a gun in real life. The idea itself is just hilarious to be honest.