I think maybe it depends how you define shit posting. If you mean trolling or posting extremely negative and low-effort content, then I suppose I agree with you about it being toxic.

But if shitposting is just off-color jokes or talking about topics you might want to keep private, I don't see that as a problem. I think a lot of great internet content wouldn't exist without some form of anonymity. I certainly wouldn't share genuine insights into my job without anonymity. People wouldn't share sexual content or secrets. Many people wouldn't share anything at all no matter how tame or appropriate. My wife over thinks when she writes and is always afraid she isn't wording things well. She posts absolutely nothing outside of Reddit.