Fedi technologies are already distributed. That’s literally what federation is about.

Blockchain isn’t private by default although some have gone that direction. Bitcoin, for example, is pseudonymous - all transactions are public to the world though no tx is tied to an identity on chain.

Any privacy features you’re imagining can be built for a blockchain solution to this problem could be built into a “normal”, web 2.0, federated solution that would be far less expensive to run, resource-wise.

It’s almost always the case that when someone comes up with blockchain as the solution to some problem, they mean distributed or maybe self-hosted. Neither of which requires a blockchain.

Check out videos involving crypto on the Cartoon Avatar’s youtube channel such as this one: https://www.youtube.com/watch?v=-xq721IAqBo&t.