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A great way to organize playlists would be - to have little sections, to which you chose the name - Genre or something entirely different. When you follow lots of playlists it's really cluttered and hard to orientate.
I have attached my concepts of the idea.
I hope you take the idea into consideration.
Have a good day.
As @neurofibro mentioned, the use of playlist folders offers the functionality you requested: click File -> New Playlist Folder, name it the genre/title you'd like, and then drag and drop playlists into it.