[lopatin]

Maybe each subcommunnity can be it's own server? Or will that not work because a user can belong to multiple communities?

[sxg]

That’s exactly the problem with replacing Reddit with a federated service. The opposite is true with replacing Twitter in which case it’s difficult to explain why a user has to pick any server at all.

[ParetoOptimal]

You can subscribe to other servers though which let's users "have" multiple instances.

[qball]

>Maybe each subcommunnity can be it's own server?

The need to do this obviates the utility of federation completely.