This is from the ""Message passing" vs "shared heap" architectures" subsection of https://dustycloud.org/blog/how-decentralized-is-bluesky/
> A world of full self-hosting is not possible with Bluesky. In fact, it is worse than the storage requirements, because the message delivery requirements become quadratic at the scale of full decentralization: to send a message to one user is to send a message to all. Rather than writing one letter, a copy of that letter must be made and delivered to every person on earth.