I’m not sure if it’s for the same reasons, but Andro.id is another example of an instance around a common intent/subject, with communities based on topics within that subject area.
Interesting concept but agree that if that was the intended means of propagating the fediverse, it doesn’t seem like it’s happening as planned (but still in a very viable way).
And to add, if you want more directly to see the data on activity of the instances and communities, switch the view to “List” from the default “Grid”