It seems strange to me to call an environment where it's popular to be rude and crude, an "adult" environment. That doesn't look like adult behavior to me at all. It also seems strange to me to imagine that it's only harmful to children. I think it's poisonous to people of all ages.
That doesn't mean I want administrators to try to impose mature, responsible behavior. I think that would do a lot of harm, and little or no good. It means that I don't agree for adults who don't like that kind of environment to have no place to go but children's forums.
I'm hoping that behavior like that is not really as popular as it looks, and that it's only bullying that makes it look that way. In that case it might help for people who don't like it, to speak up.