I think it makes perfect sense. Federation is great, certainly, but at the same time it's desirable to keep certain communities local, as otherwise they might not be able to focus on what they're meant to be about.
While the fluidity of interconnection is one of the principal aspects of the fediverse, if no particular group were able to specialize, then having different instances, or even using different applications, could become pointless.
This week I started reading Ursula K. Le Guin's Rocannon's World (1966). I had previously read The Ones Who Walk Away from Omelas (1973), and the The Dispossessed (1974) is in progress.