I think the group that says with casual aplomb, "it ain't the calibre, its where you put it..." are trying to imply that they are cool, dead-eyed marksmen that never make a bad shot nor are they ever presented with a shot that is less than perfect. And, on rare occassion, they might be right. Most of them, however, IMHO, do most of their hunting and shooting from an armchair.
Point to be made, you can drive a railroad spike with a tack hammer, but why? When there are so many better tools available to do the job.
Again, I think what drives much of the obsession with velocity is not everyone understands ballistics but we learn "speed" with our mother's milk. Standing around the water cooler, if you tell what the cubic displacement of your car motor is, about 99% of the folks will give you the "Duh" look. But if you tell them it will go 150 miles per hour, they are impressed.
I agree that most any reasonable cartridge will do for an elk, but I would have to add, "with a proper bullet" which, to me, usually means a heavy for calibre bullet. By that I mean I'd much rather hunt an elk with a 7-08 and a 160gr bullet @2500fps than a 7-08 and a 120gr bullet @3000fps.