Many use cases have been cited. But the anti-folder force is strong. There have been many multi-step, partly effective workarounds suggestions. But your quote below is spot on as to what might fill in the gap.
Exactly! Really this just needs to be a capability of Focus; to be able to sort tracks, albums, artists by values within these tags. I made this suggestion here:
I used to think the lack of this function was the result of limited development resources and low priority relative to other features users have requested. But there have been enough requests from users for various forms of inter-operability, be it folder view, capability to search and sort by custom embedded metadata, compatibility with/ability to import track ratings, etc., for long enough, that I have started to suspect that part of Roon’s philosophy is actually contrary to inter-operability.