And cries for help less extreme that suicide threats... don't actually get answered with much help, which may explain why such threats are so frequent.

I think it is very useful to have at least one moderately wise person you can freely communicate with. But it can be difficult to find one, because in our society extended families are torn apart and teenagers have to spend most of their time in Matrix (a.k.a. school) among their equally unexperienced peers, with a few overburdened and burned out teachers. There are psychologists, of course, but to visit one is really bad for signalling. Thus a sick environment is created, where it is socially more acceptable to say "I will kill myself" than "I have some problem that I don't know how to solve; may I have your attention for a few minutes, please?" :-(