Oddly enough, my understanding is that in many jurisdictions it is a matter explicitly asserting these rights. Aside from that, requesting that they be enforced when they are violated.

Agreed it would be trivial for Meta to obtain the posts. But I think the concern of most people here isn’t Meta obtaining the posts, it’s Meta monetizing them through ads and training. Would it not be in our best interest to try to prevent this?

Interesting perspective. Yet, server admins actually do have control over who they federate with. People do have control over what servers they use. Why not exercise this control?

My understanding is that one can post things publicly online but still retain rights, including distribution rights in certain jurisdictions.

I don’t think it is out of the question that the fediverse as a whole could make some decisions going forward that would make it more difficult for Meta (or other official corporations) to monetize the things we post with ads in their clients or through training of predictive models.