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.
At this point I doubt tankies should be much of a concern. What are they, 1-2% of the potential Dem voter base? I’d sooner worry about the indecisive ones who have seen the performances in the debate.