Yeah, it's an anti-spam measure, so that a bot account can't fill the forums up with a hundred ads for sports betting or boner pills or whatever in a few moments. We keep up on the bots around here pretty well these days (knocking on wood for luck), but occasionally they do get through- this helps limit the damage.
I don't know which threads are the problematic ones, if you let me know what you want done I can prune them or combine them without any trouble- just want to make sure I don't take the Admin-Hatchet (TM) to the wrong posts first.