This article on Teen Culture from a while back completely misses the point about Boomer (born 1943-1960) moms and dads. They didn’t “keep up with new trends” in the sense of trying to be fans of every new pop group. Rather, they perceived (correctly, IMO) that music from all the new pop groups was a pale wannabe reflection of the pure glory of the vintage rock of their own day. And so they condescendingly accepted it and even hummed along with it when their own kids played it. Boomers enjoy most of their kids’ music precisely because they sense it to be derivative of their own. Rap of course is an exception. It is not derivative (but it is also a Generation X (born 1961-1981) phenomenon). But this is the exception that proves the rule, since this is a genre than many Boomers have not and never will embrace.
As for Mexico, one thing I learned in my recent trip there is that “emo” is a code word for a subculture that we would call “goth,” that is, culturally to the left, whereas the punkers I am sure were standing up for traditional machismo, that is, the cultural right. In other words, the fist fights were political.