That kinda highlights the problem. Search "scuba". There are 4 separate communities:

There are 39 total posts between them, but the one tied with the most posts has zero active users. The one with the most comments ranks 3rd in posts and only has one active user. The one with the most active user only has 2 comments according to the search.

If I search the same term on sync while signed into .world, I get different communities and very different user counts for those that are in both searches:

None of these communities are really active. But between them they would have had have the user base to get it going. Finding a community and getting the critical mass needed for it to thrive is made much harder with this amount of fragmentation.