There's been a lot of discussion in the YA book world about how YA books are becoming less and less about teen readers and instead, more about the interests of adults who like reading YA. Some claim that the community in fact isolates teens. The oft-cited statistic that 55% of YA is purchased by adults, which came out in 2012, and the fact that more YA novels are featuring college-age protagonists, as well as teens who are 17 and wildly independent, further uphold this argument.
It's hard not to wonder, too, if the fact that many refer to YA as a genre, as opposed to category of literature, is why it's so easy for teens to be pushed out and for adults to feel more ownership.