Skill over size, that is true, however it places the kids at serious risk of injury. More so when the big kids get frustrated at losing. Teams who try to make up for lack of skill with brute force, and clueless parents who think "that's lacrosse" do a real disservice to the game and the rest of us have an obligation to call it out when we see it.
Agreed too. Particularly at ages when some kids are hitting puberty and some aren't.
Not rocket science. US Lacrosse requires Proof of Birth and establish software that allows tournaments to offer online registration and waivers that cross reference US Lacrosse database.