I am an open format dj and my collection contains a lot of genres and sub-genres
I created my folder structure in such a way so that I can sort my music as soon I download it.
example: I download a liquid drum & bass song and it goes to Music / Drum & Bass / Liquid / 2019-3-Summer
example 2: another drum & bass song and it goes to Music / Drum & Bass / Melodic & Uplifting / 2019-3-Summer
example 3: bass house song goes to Music / House / Bass-House / 2019-3-Summer
The same for hip-hop, reggae, dubstep, dub, minimal, techno, funky house, breaks, deep house and so on...
So just imagine my workflow every week checking and syncing over 30+ subfolders with my playlists... I'm at the point of just copying my folder on to a USB flash drive and using it the old fashion way in CDJs.
A solution coud be:
User: sets root music folder
Rekordbox: Creates folders and playlists based on that folder structure. (Creates folders & subfolders until you reach the last subfolder and make that a playlist.)
Or a different solution would be playlists and sub-playlists (in which a playlist can contain songs and other playlists) and sync that with the file structure)