Oh and trolls and bullies commenting on your profile just don't seem to ever get banned nomatter what horrific shit they post.

They certainly do if you report them. Losing your community privileges, including the right to change your avatar, is something Valve does to people who violate the community rules. But there is no automatic system. You need to report them.

As for the rest: It's a video game store. Think about how many of the users are children. It's why there are curators and ratings for damn near every submission. They used to even have ratings for the forum topics back before they were integrated into Steam directly; they probably should bring that back.