Full transparency: I operate such a community. It's tiny right now. 11 VIPs. I'm not going to link it.
I believe there's a need for private, professional communities that aren't too big or aren't too small. I don't exactly know what this number looks like to be fair.
What are your thoughts? How do you feel about the fully open, public nature of communities like Hacker News, certain subreddits, etc?
If it is around a specific niche, then it's a different thing.