Regardless of phenomenon or fame, aren't crushes always about the crusher? As a male, I never really experienced the phenomenon of a mass crush in the way girls do, but certainly I know the feeling of having a crush on this or that particular girl that I knew from wherever. Even in that case, I think we tend to fixate on a person who seems desirable, and almost fetishize them in a way that makes the person a lot more than they are, perhaps a s a measuring stick for ourselves. Of course then we discover--if your object of desire reciprocates--that we're all just imperfect humans. Maybe that's the point of fixating on the unattainable--one can't ever discover the other's humanity.
On a side note, as I was reading this I couldn't help but think what it would look like for the shoe to be on the other foot. What if every time some famous actress walked down the street she faced hoards of teenage boys who would rape her if given the opportunity? We would declare a world class sociological catastrophe. Well, at least these girls have on line forums to discuss their interests now; its probably less isolating than having a Columbine crush in the pre-Tumblr era.