Moreover I don't think these need to be on a single scale. Like, trauma isn't "more" than pornographic, it's just something completely different (ideally).

There can be a scale of safe to unsafe for a variety of reasons, and people might be able to filter what they see more proactively based on their own tolerances (and interests).

But then again complexity can be a deterrence. Tagging and cataloging can be a big content management problem and I think most want to do the simplest thing possible.

But maybe content advisory could be a crowd sourced effort, using a up/down ranking on explicit categories just like we can do on posts.