Our brains and bodies never stop changing. There is no point of “finish developing”. and even if there was that wouldn’t prove people before that point are stupid. The whole idea is garbage that bigots use to justify hating on specific demographic.

and “lacking any real life experience”? well, sure, because we barred them from entering adult society. They have been legally and socially prevented from gaining any of that experience. That’s not a problem with them, that’s a direct result of us treating them like shit, and creating a problem that need not exist.