I don’t use Bookwyrm either, but coming from the perspective of Storygraph, I don’t really think the average user there wants their review to become a talking point. I’m not really writing them for deep discussion or analysis, just my off-the-cuff thoughts on finishing a book, more for my own sake too. I also don’t want to see threaded conversations when i’m skimming over reviews to decide on a book to read. Hence why I think it makes more sense for a publicly follow but don’t interact type of federation for those types of services.
Because hating on Threads is cool right now. The spotlight should be on Meta as a whole.