Takes a bit to get set up with something passable. The default Lemmy UI is kinda shit and you have to figure out which apps to use to make it work for you. It can feel a little unpolished initially.
Niche communities just aren’t there yet. There is a lot of effort in creating them, but low engagement. It also doesn’t help that federation can mean communities on one topic are divided.
Content can get a bit stale. I feel I see fresh content for about an hour a day and then have to wait another day before the next batch. When I browse throughout the day I start to notice the same stories popping in my feed over and over. Sometimes this happens for days on ended with one story just kinda coming back.
I think people don't like having to figure out what federation means and run away without realizing that they didn't need to know what it means to participate.