I don’t think this is the exact cause for the situation, but having more book related forks would probably just do harm by splitting up the audience. The book reading trackers are absolutely dominated by Goodreads, and any alternative desperately needs as much user concentration as possible.
BookWyrm was my first dip into the Fediverse, back when I was looking for an alternative to Goodreads.
Really surprised it’s the only book related fork of the fediverse here
Do people not read any more?
Most people I know who read a lot use StoryGraph, and mostly for personal tracking, not as a social app.
I don’t think this is the exact cause for the situation, but having more book related forks would probably just do harm by splitting up the audience. The book reading trackers are absolutely dominated by Goodreads, and any alternative desperately needs as much user concentration as possible.