I assume Mastodon is equally capable of recommending things, but if it's a common problem that people aren't patient enough with then it could be fatal. It's still an open question whether federation as its been used thus far is really there yet. I'm not entirely convinced, I'm glad it's being tried. I'll take a stab at it, I've worked on P2P distributed key-value storage for years. No huge ambitions though, I don't really care about this use case. My conception of federation is closer to newsgroups, ideally it's a global namespace for a topic but the feed is controllable by, effectively, a federated moderator web-of-trust that users can selectively opt into and demote mods as a personal preference. Maybe someone else can do it because I'm so disinterested.