Because when you're two inches from your non-moving, sleeping, unaware target doesn't know that you're about to pop them it's a little easier. As for the mob and CIA I seem to recall that the mob still favored machine guns and the "you don't see me here" guys I didn't see in Iraq we're still carrying ARs/AKs and service pistols.
Ask yourself this, if the .22 is soooooo good for ___________ why doesn't the Military issue them as rifles and sidearms, why don't the police do it either?Think of the savings in ammo budgets if they were to go .22 and the ease in shooting them, but they still don't use it. I wonder why?
Sure a .22 will kill some one, but it less likely to do it quickly.
Add to that that rim-fire pistols can be ammo sensitive, the ammo itself is known for high failure rates.
Edited to add, when something still has trouble killing rabbits and squirrels, I'll leave it at home when carrying for defense against two legged threats.