The whole "adults can't have fun" attitude is incredibly frustrating to me -- and particularly so in relation to fandom, which was, of course, created by adults (and mostly adult women to boot).

I think some of it is rooted in the current trend where anything you don't like is somehow equated to pedophilia and therefore adults are inherently EVIL. I think a lot more is rooted in sexism and the idea that women's pleasure is inherently suspect.

And then, of course, there's the thing where anything you like as a teen must inevitably be disclaimed and shunned as you become an adult because OH THE SHAME!!!!, so naturally adults can't possibly like the same things a teen currently likes, and if they do, there is something deeply shady and wrong about them. I think some of that reaction is just an inevitability of growing up, but it's been strengthened and warped by the pedophilia craze and pervasive sexism, and the resulting stew is doing nobody any favors.