Always remember that uploaders and taggers don't read wikis, if they have a common understanding of a very common concept. Basically everyone thinks he knows what a succubus is, which leads to the problem, that a hard definition is useless for danbooru. If we make a definition that is to specific, people won't read it, because, as I said, they have a common understanding of a succubus. If we create a definition that is open for different concepts it's going to be useless. Just google succubus and you will see, that we won't satisfy anyone with a open definition. Are they searching for a WoW succubus? Are they searching for the mythological one? Do they need to have wings or not? This leads to the problem, that succubus are very hard to tell apart from basic demon girls in sense of tagging. It would be more easy for everyone in such a case, to just search for exactly what they want, like "red skinned demon girls" etc.
Sometimes it seems favorable to have a basic tag for widely known concepts to please as much people as possible. I think that most people who come here to search for fetish art don't care if we had a wide definition of succubus, as long as they are able to search for succubus. Most will only care about the concept, not our hard definitions. But, like NNT explained, it will just lead to a lot of problems for tag gardening and searching, if people pollute such tags with garbage.
On another point: We don't keep tags because of tag limits. If we did that, we would have to implement even more combination tags, which will basically lead to more tag gardening problems etc. You can either support the site to be able to search for more tags or you have to use another booru, but then you're missing out on the active tag gardening user base and, once again, have to live with the trash tagging of other boorus.
