This is only tangentially directed at your reply, but this is the kind of statement that I'll sometimes hear other parents say, and it makes me think that they've completely forgotten what childhood was actually like. Like, the idea that normal, fun activities and sports are bad because they bear some abstract resemblance to adult violence feels very contrived and misses what childhood play is about.
It's not really that abstract. You smash the shit out of a cardboard box and candy comes out. Breaking things is not fun. I also hate youtube videos of people breaking stuff for fun.
Yeah I'm not saying it's bad for the children, but it's unpleasant for me. It seems violence is a concept that gets deeper and uglier as you grow. For young children it's often abstract and maybe harmless. I just read a book to my child that turned out to have violent scenes that horrified me a bit but he barely thought about it and only in technical terms (like where is that artery ripped by the wolf). Same with people that had fun watching horror movies as teens, then find them unpleasant when they're older.