gratuitous--
being without apparent reason, cause, or justification
I never said sex, violence and swearing should be cut entirely but why use it if for nothing more than just to use it? Did I go "mother f-----" when I slammed my toe into a piece of plywood and broke it when I was 15? Absolutely. But it wasn't every other word out of my mouth, either. Reality doesn't always translate to the page regardless of whether it's YA or adult fiction.
Without having read any of the edgy titles, porn without plot, logically speaking, isn't something that's marketable in the YA genre. Neither is violence just to have it. If it's just a big old teenage orgy where everyone gets slaughtered at the end, I'd want to say that'd be a pretty hard sell in the YA market. I'll be the first to admit that my knowledge of the genre is pretty limited but just thinking logically, some things, like the murder orgy, just wouldn't sell in YA. That's what I mean by gratuitous.
Sex, violence and swearing are rife in teenage life but, like you said, it's handled differently because of the YA genre. I'd also want to think it'd be handled with a touch more restraint than what one could find in adult fiction. I'll have to pick up one of the edgy YA books, though, to give myself a better idea of just what is acceptable in YA.
Any recommendations for "comfortably edgy" and something that pushes the bounds of extremes when it comes to edgy YA? I do want to say that parents don't give their kids enough credit when it comes to deciding what's "too mature" for them. They can certainly handle a lot more than what their parents think. On the same line, if I had a teenager or a middle grade kid, I wouldn't want them reading about how to disembowel a human or reading something that is rightly porn from a book classified at YA suitable.