Consider the way BitTorrent works. You don't have to know what your peers are going to be, or where. You don't have to trust your peers: as long as they serve blocks with correct hashes, you are safe to take data from them. Equally, they don't have to know you or trust you.

It, of course, does not work for email. OTOH protocols like briar [1] theoretically could.

[1]: https://en.wikipedia.org/wiki/Briar_(software)

Alright, so how do you propose we decentralize the Internet physically? Because that's really the crux of this. And what has allowed the mass surveillance by state actors.