After becoming an adult and learning how my father works I've learned that when he says "shot placement is all that matters" I know he really means that it's really important and that's his way of emphasizing that.
It may be an overstatement, but I would argue that his feelings aren't simple. Look at this way, "Having money is the only thing that matters in investing." Not true, in theory...you can put your $1,000 down at 3% interest and make a little money. But the guy who can invest a few million is still making more in interest than we'll pull down in a year.
Same thing with calibers. It's all about shot placement, but you have to get to the point where putting a shot in about the right area is enough to give you a good result. Shot placement, and investment choice is easy to change. Caliber, and bankroll is not...