The thing is, MusicBrainz, and by extension, BookBrainz, do not have stylerules but styleguides.
What that means is that guides are there to help you, because RL isn’t cookie cutter - there is always going to be edge-cases and weird ones, and for that we need to make educated, sometimes styleguide interpreting individual changes.
Edit: outsidecontext explains it much better than I in this comment: Also remember that guidelines are…