There’s a lot more to what playing shooters teaches you than simple aiming mechanics. Aiming mechanics are based in large part on muscle memory, which of course can only really be achieved by having the actual piece of hardware that you are trying to build the memory for. This has to do with not only visual acquisition, but literally the weight and balance of the weapon you are using. If they build an accurate in every detail weapon you held in your hands to play these games, your learning would be almost indistinguishable.
What playing lots of shooters does teach you, is how to clear rooms, how to spot and prioritize targets, how to know where threats are mostly likely going to come from etc. Your tactical awareness, and your reaction time to those decisions, can and does get “trained” by playing shooters, especially the more realistic ones. The other thing it does, is desensitize you to violence. Once again, the more realistic, the more pronounced that process is.
I’ve become very good at spotting cameras for instance.
I think there is a lot of hyperbole on both sides of this argument. Trying to state that violent games have no impact on people that may have violent tendencies to begin with strikes me as pretty foolhardy. I don’t think games can necessarily create killers, but they can most certainly facilitate progression of violent tendencies in people with pre-existing proclivities, if only for the confidence building and tactical awareness they offer. Even if it’s delusional, it can build a belief in the user that you are “getting better”. That’s the dangerous part when you’re dealing with someone that has some sort of psychosis that gets fed.