Basically, there isn't much reason (maybe NO reason) to mount your optic farther ahead than you need to in order to clear whatever parts or real estate on the gun you need to. Mounting a scout scope on a bolt-action rifle to get it out of the way of the top-loading action made some sense. Moving an optic forward on a rifle that has no need of such, isn't gaining anything. It isn't faster because it's farther away. You can't see more because it's farther away. It's JUST ... farther away.
With the good, decent, and even excellent low power and low power variable scopes available today, you can build an exceedingly fast-on-target AR that can be shot both-eyes-open very easily at lower magnifications, and then let you zoom to 4x, 6x, or even 8x, which is enough for shots way out farther than you have business shooting that round at a game animal, certainly.