They will do that if the username and/or email address is already taken. I’ve seen it on my own instance. There are possibly other reasons as well.

That’s great, although I’d like to see some others up there as well to keep the fediverse healthy.

Does anybody know what the hardware specs are that lemmy.world runs on? It would be nice to get an idea of the hardware requirements to scale up that far.

Nice. I hope this momentum continues to grow.