http://awuuwa.i2p/webpages/Fediverse%20vs%20Retroshare.html
To achieve a similar functionality of talking to anyone on mastodon servers, there could theoretically be ceveral big nodes that everyone can connect to, which would then serve as the middle nodes in the friend-to-friend network. But instead of them being a centralized server with it's own rules for the users to follow and which manages all the user content, it's just a node that passes data trough itself, nothing more. Even if one of those big nodes gets taken down, it doesn't do any...