Yep. Given the so-called 'psychiatric community' still considers this a 'fetish' (in other words, they still think we do it for sex-kicks), 18+ seems a very safe policy to keep out of undue legal trouble until said shrinks pull their heads out. CSI's "King Baby" episode did us no favors, neither.
They might not have realized that ABDL (for Teens it's TBDL & for kids it would be KBDL) is not Pedophilia plus it DOESN'T Have any Sexual Interactions.
That needs to change in the future because ABDL (for Kids it's called KBDL & for Teens it's called TBDL) is independent of Pedophilia. I think the schools you were at didn't have enough education to include it.
I'm a '60s Baby...a '70s Child and an '80s Teen. I'm a product of my time, fighting hard to adjust, doing okay...but not perfectly. The future is not mine; I am obsolete. It's for you younger ones who have more time. Best I can do is cheer from the sidelines.