I personally think they're really good. I've just onboarded a friend onto Hive and the communities is literally the first thing she was drawn to. For new people creating content that suits a community makes so much more sense than trying to build a following randomly. I like that communities get a cut of the rewards too, it gives them some value to play with and upvote the quality pieces, which encourage people to create more quality pieces... which in turn brings value-adding content to the platform as a whole.
On PeakD in particular, communities seem well-implemented. I haven't personally used them enough to notice any pain points, but overall I think they're great.