I don't believe a tag can be "over used" unless it is use more than necessary in the submission's tag list. One more thing I would like to point out about one of your statements generalizing anthros and furries, "All furries are by definition anthros" is that even tho there is some confusion among those inside and outside the fandom is that NOT all furries are anthros, but some are actually zoomorophs. Zoomorophs is something that are given the attribution animal characteristics or qualities of a god. A werewolf or a demigod would be such an example.