Well Personally I don’t think it makes sense to do that (logically) at all.
But in a way, practically and space wise, I do understand why you would want it. But as the folder is the defining structure for the content (tracks) to be shown/hidden it wouldn’t be logical for the folders to be hidden and only the tracks (or some of them) to be visible.
In that case I would stop using folders as it seems like you really do not want to use them in the first place.
Or am I misunderstanding something in your thought process?
Is what you are asking for basically a way to temporarily hide the graphical folder tracks but keeping them as organizational tools?