When dealing with high caliber rifles you want a transference of energy and if the bullet stops in the animal,all the energy gets transferred,unlike with a bow where you want penetration.

Naturally,you need enough penetration to get through the hide and bone that is encountered upon entry but beyond that,it isn't the main goal.

Of course,thicker boned animals like elephant need more penetration than whitetail but we aren't looking for passthroughs.