I wrote most of a really long reply and then trashed it because it just sounded more and more arrogant. I think your summary does a better job. Humans do love to categorise stuff, and sometimes it's useful in a top level way (which part of the bookshop do I need to be in), but it's always at risk from cross-category content or increasingly diverse and deep categorisation which then stops helping. Are we reading a crime novel, or a romance novel, if the two investigators are having a relationship, but the story focuses on both equally. Which bit of the book shop does it go in. The same debates and arguments rage in all areas of art.