Once you get to 18s everyone, players included, know who is a baller and who isn't.
Most parents that make it that far settle down. The kids are usually commited so that parental stress is gone. At that point the team and players have different goals. Maybe win a big championship or sharpen skills before college. Most drama occurs at 12s and 14s. I think a lot of it comes from parents who are starting to realize that their DD isn't gonna end up at UCLA.
I still run into 18s, or their parents, that somehow remain confused. I've also seen older teams that performed well on the field that were terribly dysfunctional and fell apart seemingly overnight. That said, I agree...16/18 does calm down quite a bit in terms of gameday parental volume. There was some 14U drama, but I thought 12U was the worst with 10U close behind.