I played a lot of football. Beyond poorly trained teenagers, I’ve never heard a coach or a player advise leading with the helmet. Body, arms, shoulders, pads yes. head? Nope. Too dangerous to the neck and head. When you play at the college/pro level, that kind of behavior will get you (literally) killed.
Keep in mind this was in the 90's. For sure we never had a coach say "nail that guy with your helmet", but every game had dozens of these kind of impacts, the worst typically on special teams.
It was less disciplined in high school for sure, but there was still lots of high speed helmet-first crashing going on in university.
