It is probably due to a number of people stopping using their alts after some instance hopping.
Also a few people who came to see how it was, and weren’t attracted enough to become regular visitors.
Curious to see at which number we’ll stabilize.
Next peak will probably happen after either major features release (e.g. exhaustive mod tools allowing reluctant communities to move from Reddit) or the next Reddit fuck up (e.g. removing old.reddit)
Stats on each server: https://lemmy.fediverse.observer/list
If you are explicitly aware that different instances specialize in different concerns I can absolutely see the use for a feature like that, but most people want a feature of that sort just so they can “paper over” federation and pretend to have one giant community with one giant moderation policy / culture / priorities.
And that is before getting to the absolutely horrible idea of automatically generating multi-communities by merging communities with the exact same name regardless of their instance.