Part of it is we've seen too many female athletes plateau at the level they achieve as a junior. It really doesn't help them to be in the spotlight as a twenty year old. I'd rather these women have high aspirations, but encounter low expectations.
Hard to say about plateauing. This may the making of one of the greatest female runners of all time or she may only improve a little more. Even so, at 8:46, she pretty much equals the best US female this year (Katie Mackey @Monaco), so not too shabby at all!