You are probably right on your pessimism. Growing communities is hard. That’s why I’m trying to focus the efforts in a few, but more than 1 community. Which community will succeed in the long term is impossible to predict, so I think it’s better to just keep trying with different ones.
I find !shittymoviedetails a very good attempt. If I get it correctly, is like fakehistoryporn but for movies, right? I think that’s the kind of niche-but-not-too-niche topic that could work. I’m not very familiar with the format but I will keep it in mind in case I find something worth posting.