How much effort did you have to put into Reddit to prevent subreddits from disappearing due to going private?
In the Fediverse, there's one more layer of indirection. The instance. For better or worse, Beehaw controls some of the largest groups, whether or not that's due to their moderators or whatever that's on them.
I imagine that we're mostly Reddit refugees right now, this concept of "instance" is alien to all of us. But its really not much different than a "group of subreddits" that somehow got a magic wand and was able to go private together (or share users, etc. etc.).
I remember in Reddit, tons of communities would go private all the time, mostly because they got trolled so hard by other invaders that they had to do so to protect their culture. Whether that's the "trolls fault" or the "community's fault" depends on the instance. But it looks like Lemmy / Fediverse has new tools to deal with this age old issue.