Retronautickz

Reddit had/has the same problem. It’s just that federation makes it way more obvious on the threadiverse.

All platforms on the fediverse interact because they are part of the same protocol, ActivityPub. (While there are more federated and decentralised protocols, “Fediverse” refers to ActivityPub based social network)

Other federated and/or decentralised platforms have other protocols, for example Diaspora* which has its own protocol, also supported by Hubzilla (which main protocol is Zot and also supports AP), Friendica (also AP and Ostatus) and SocialHome. Or Ostatus (GNU Social, Pleroma (also AP), and Matrix (Matrix)

A social media can interact with other social media that share the same protocol.

so Friendica can interact with Diaspora, Lemmy and GNU social, because it supports Diapora*, AP and OStatus, but the other three, being mono-protocol cannot interact with each other.

No federated alternative as of yet. It’s one of the platform types that the fediverse is lacking.

Dreamwidth (which is not a platform to host fanfiction, but rather to discuss it, share recs, etc) has had federation proposals, but nothing has come out of them.

WriteFreely is in the fediverse, but it’s more of a blog platform the style of blogger, wordpress, or medium.