There is another facet of poetry written by teenagers that none of the other w/us discusses---a small number of teenagers who write poetry will spend enough time working on the mechanics and craft of writing and editing poetry that they will become reasonable poets.
Poetry, like all art forms is 10 percent inspiration and 90 percent perspiration. Learning the craft of writing poetry and editing it to a publishable standard is a long and thankless task that few people carry off, but if teenage angst can be channeled effectively, a valuable skill can be learnt by the teenager.
It is, of course, unlikely that the teenager will receive the 10 percent inspiration during their teenage years, which means that for the skills to bear fruit, the teenager must continue to write and edit well into adulthood. This is relatively unusual, since many teenagers `grow out of' writing poetry and even many who have developed non-trivial writing skills look back with some embarrassment at their teenage poetry and never write again.
…and yes, i'm one of those who developed the skills but no longer write. There was a period in my very late teens when I was writing and editing 30 hours a week.