Although I agree that is how things work now, one could imagine a different approach:
For instance, I could maybe control who my content gets federated to. That is, if I decide I don't particularly want my content blasted to certain places that my instance would not call any blocked ones with my data.
If that causes some issues with ActivityPub, you can imagine encrypted blobs that could only be opened by others with a shared key.
We don't need to achieve perfection out of the gate, to me these questions are worth discussing so that we can build out more high quality tech for the fediverse, let's not try to just immediately shut down discussion.
Any episode involving the prime directive in TNG, basically. Picard has to be convinced to do the right thing by others in violation of the prime directive.