People must use what they have confidence in. Often with more experience and knowledge one learns that 9 times out of 10, or more - it really does boil down to shot placement with a good bullet.
That said, when hunting dangerous game the consequences for anything less than a very quick kill - might get one badly hurt or worse. Those applications warrant any surplus in power, for lack of better words.
I have never failed to kill game because my chosen weapon "lacked power"
Ballistics offers a great study and discussion.
Range time is the great equalizer
