I blame Soccer.
Why? Because Soccer players are good at running and performing skillful 'shots' while 'playing' their deadly combat simulation. Nevermind that they never actually touch a gun (or anything with their hands, really); the entire thing is geared towards training future killers.
The fatasses who I see playing Half-life, Quake, and Unreal, couldn't kill me if they tried ('Safety? what's a safety?) but a soccer player...