It is, if there are no other categories of interest most people won't join, plus it gives off this feeling of being nerdy and niche.
For example I want to talk about all kinds of topics, but all I'll find is crickets since the target audience isn't there.
Honestly, I've seen just about everything on nostr. If you just start talking about what you want to talk about people will find you snd it'll become it's own subculture here in nostr. See it countless times now.
If you can actually find something that no one has yet talked about then guess what, if it interests you, you're probably going to become the OG of that community once you start it.
So, what are you looking for?
