To go back to the original question, lets put it like this. Why dont we use .373H&H for everything? Well, with more than enough gun we can expect excessive recoil, which will result in flinch and loss of accuracy, we can expect massive muzzle blast and flash which is not conducive for good hunting and they are more expensive to shoot.
I totally agree with a .308.
"Beware of the Man with one gun...he probably isnt into guns enough to be safe with it".