Rationale:
* The spoilers tag is the most frequently removed tag from the default blacklist.
* It's frustrating for regular users to have posts randomly hidden because of trivial
spoilers from a series they don't care about.
* The spoilers tag is used way too liberally for things that aren't considered
spoilers on other sites.
* If you're looking up fanart on the internet, you should expect to see a certain
level of spoilers.
* The tag is used very inconsistently, with some characters like Nia_(blade)_(xenoblade)
getting the spoilers tag half the time and the rest of the time not.
