The concept of folders and the concept of groups can be merged.
In this concept, when a folder is created it could have the option of becoming a special kind of folder I am calling a 'group folder’ - think cross between a folder and a group.
In these special folders any track (or sub folder) that strays into it gets its routing dominated by the folder, until it leaves again.
So, you create yourself a folder and you call it ‘brass’. You have another folder called trumpets - with three or four trumpets in it, and a few stray instrument tracks called - trombone, Tuba, you get the picture. As soon as the track or folder enters the group folder, the routing gets hijacked by the ‘group folder’, just like a fly in a web. When a track leaves this folder it’s former routing is restored. If it is dragged from one group folder to another, it takes the routing of the last group folder.
The group folder has a destination route for all its instruments (just like a group).
No more fiddling around with group routings, the folder takes care of it, simply by dragging. You just dream up your group folders : strings, brass, guitars, vocals, then drag your instruments in. SO EASY!
Such group folders could be tiered, simply by making one group folders output point to another.