General tags were always fun discussions on whether or not they had a purpose. The best description I have for most of them is "kink filters" used for either blacklisting or searching for those things.
These types of search words can usually be generalised into a few categories anyway. On top of that the general idea that whoever suggested the tag got stuck maintaining it until it became common among users, which will never happen if it's not a very broad concept for a tag.

I still smile thinking back to discussing the concept of "dressing" vs "undressing".