I've never really understood the appeal. Goodreads is a pretty good source for synopses, and IMO that's it. The reviews are mostly shit, the ratings are useless and the recommendations are pedestrian at best.
If book sites were restaurants, Goodreads would be McDonalds.
Is this an app-specific issue?
I've seen a few references to this in the last couple of days, but I don't see it myself. On Firefox (and presumably on any browser) I just see one version of a crossposted thread, with a note at the bottom that links to the crossposts.