What is so difficult to understand? Having a dedicated 22 upper that is the same as your go to rifle is the way to go for training since manual of arms is the same.
Practicing with a 10-22, etc, does not teach you to work the controls on an AR, practice with the .22 unit does do so.
An AR, like most auto-loading rifles, is a pretty simple beast. Pulling on the charging handle and pulling the trigger I've never found too complicated. Getting the shots on target is where the practice is of most benefit, regardless of the "manual of arms".
Good thing too, if you get used to training with your .22lr AR you'll never pull the charging handle back far enough to chamber a .223. Also many .22 kits don't have the last shot bolt hold open.There is a quite a bit more to weapons manipulation for an AR than simply pulling the charging handle
I laugh every time I see somebody who is so worried about swapping mags and firing lots of rds that they just overlook the fact that if they need to swap mags in a real fighting rifle, they are just missing way too often