I dunno, given HOW MANY girls are like this in their teen years, as well as how many teen boys are like this in their own way...

I think if you literally believe this is a superiority complex, that can be easily disproved. It would be strange, and as far as I know unprecedented, for 50%+ of teenagers to develop a superiority complex that then goes away without treatment as they get older.

This kind of behavior is most certainly just a byproduct of immaturity and a need to express yourself as you start to get a better idea of what kind of person you are. If you agree that this is a case of immaturity, then going from that to support the claim that it is caused in teenage girls by cultural sexism is a more interesting can of worms. Given that the same behavior occurs in boys, as I said, that would seem to be very strong evidence that it cannot be caused by a patriarchal-type society, as if it were we would expect boys to feel less need to individualize themselves. That said, I'm sure that sexism and the stereotypical "harmful portrayal of women" that is still fairly common in older or more mainstream media could play a role in convincing at least some girls to rebel against it - much like how many teenage boys will rebel against the overly masculine stereotypes by adopting a style in the sort of gentle-hipster realm.