Your example, whilst pertinent, doesn't go far enough.
I'd like for instance to have one overall guitar folder, then sub-folders for bass, acoustic, electrics, then split the electrics out into clean/distorted
And drums, have one top level for drums, then sub folders for kicks, snares, toms, cymbals
Vocals? Lead Vox, BU vox, Harmony vox.
Or you could split them according to Fx used - delayed vox, chorused guitars, I'm sure this is just the tip of the iceberg of what you could do with a fully featured nested system.