One thing I have noticed by examining fanfiction tags is how they are both used for useful purposes, but also used as a way for the author to inject humor. The tags can act as a free stream of consciousness for the author. The tags can help identify the key characters and worlds in the story, but also can be used by the author as a way to make jokes or lightly mock their own work.
yes! this reminds me of how Tumblr users would post a blank text post and the content of the post would be completely in the tags. often stream of consciousness and personal notes.