Too much gun, not enough gun, they're both rhetorical questions.
The idea is to hit vital parts. Heart, Lungs, Central Nervous system or to cause enough tissue damage and hemorrhaging that blood loss leads to death.
It's not the arrow, it's the Indian.
If the person behind that is utilizing said tool (rock, knife, bowling ball, hub cap, rifle, shotgun, bow and arrow, etc.) can't direct it to the place where it will cause one of the previously mentioned things to happen, it's not the fault of the tool.
People, as well as animals, have been know to seriously hurt/kill themselves or others just by chance and/or good/bad luck, sometimes with nothing more than the clothes/hides on their backs.
I think that a lot of times we tend to make a big deal out of little or nothing at all.
That being said, .270 Winchester, .280 Remington, .308 Winchester and/or .30-06 Springfield are probably the cream of the crop for one size fits all compromise cartridges.