I've recently started three communities, right now they are basically just me posting journal entries, or things I organically find along the internet.
[email protected] Is all science based journaling
[email protected] Is casual LCHF discussion
[email protected] Is casual Carnivore discussion.
The last community got lots of negative attention, the name was unfortunate, but that is the name in the literature and it is triggering for some of the other lemmy users. ASF is used on occasion, but that is mostly in agriculture literature.
I've found it is useful to have a journal that you can link to, and discuss with people, so its a net positive use case, though it is very niche.
For the casual communities I look for content that can prime the social pump so people feel comfortable interacting (mostly youtube cooking videos for now)