Just out of curiosity, if the sport is so violent/unsafe for kids, why not ban it for under 18 players ? Or is it that, only a small subsection of the american

Just out of curiosity, if the sport is so violent/unsafe for kids, why not ban it for under 18 players ? Or is it that, only a small subsection of the american population find it violent/unsafe and the rest are completely fine with it ? I find it difficult to understand how parents could allow their children to play a sport knowing it might cause permanent brain damage to his/her kid. Maybe we're missing something in this debate ?