But just because !books hypothetically exists doesn’t mean !books or !books have similar enough content. You can already view these communities from any instance. You’re essentially trying to apply something like federation on top of something already being federated. They can all have very different rules and different content.
There is a drop in monthly active Lemmy users (from 65k to 57k) (lemmy.fediverse.observer)
It is probably due to a number of people stopping using their alts after some instance hopping....