Bullsh!t, u never see a guy catch one behind their back in a game, doesn't hurt anybody to catch a couple like that in practice, unless u try to catch one between your legs and u miss time it and clip your nuts
During fielding practice I muffed one at short. Next one my Dad hit one harder, another blunder. He kept hitting them harder and harder until one bounced up and hit me in the jewels. I was on the ground for a while.