Communities are tricky two sided challenges. Nobody wants to join an empty community and nobody wants to write for an empty community. It requires A LOT of work. I ran a community for over a year and experienced this first hand.
The trick is to seed the community with a good number of active users who share interests in the same subject. The interactions must recent so others see they’re not joining ghost towns.
The issue I see with nostr moderated communities is that you can see all of them right away and most are empty. Big reason not to join.
I think the way to solve that is to have a global cross-community feed and to surface active communities.