I’m “the public” and you are “the public” so again, I ask you, how would it be decided what is harmful and who exactly would do the deciding?

If you mean that the public decide by making their own decisions on whether to read something or not then that sounds like a good system to me, as I’m happy to make my own decisions. I’m also an adult who respects the right for other adults to make their own decisions, especially about what they read.