And yet the stereotype of the dumb football jock who's had his head knocked a few too many times has been prevalent as long as I can remember. It's just that previously it was used as a punchline in sitcoms rather than seen as a serious health risk to our children.
Except for 'Varsity Blues' (1999) I guess, and I'm sure other examples, where the evil coach telling the kid to play when another head injury could kill him was a main plot line.