It's irrelevant to you, but a community doesn't have to be massive for it to be important to it's users, it just has to be big enough for people to get something out of it regularly to keep the existing userbase engaged. Lemmy pre-migration is a great example. But if enough people leave in a short timespan it's really hard to keep the remaining userbase engaged after that drop-off. XMPP is a good example of this actually happening, I had a bunch of friends on there for years. When google pulled the rug, a lot of users lost a lot of their reasons for sticking around. It's a shell of itself now.