I don't understand why anybody would want to have it any other way. I already had hundreds of 1-song albums in my library before Apple Music. Why would I want to have all songs of an album in my library if I only ever listen to one (or handful) of songs in an album? What is the problem with 1-song albums? Singles existed pretty much since the beginning of recorded music.
If I like a playlist, it means I like the songs in the playlist (at least most of them). Which means I of course want them in my library. If there are a few songs I don't like in the playlist, I delete them again. If there are only a few songs in a playlist I like, I only add those few songs individually. One of my most listened to playlist is a smart playlist of the most recently added songs (I think currently set to added in the last six months). It contains all the great new stuff I've discovered recently, all the songs I discovered via the radio, music podcasts, or now playlists from Apple Music. Why wouldn't I want to have all the individual songs I discovered via playlists in it? Why wouldn't I want to have all the artists I discovered listed in the list of artists in 'My Music'?
Well, playing the playlists doesn't add them to your library, so I don't understand why you would avoid even just merely playing them.
Focussed on what? The only thing I can think of is that you want keep the library of the stuff you own separate from the stuff you are renting, the stuff you have 'bookmarked'. But that doesn't explain your dislike of 1-song albums.
So you want to add yet another layer in this? On top of playlists and songs presented to you (in 'For Your' and 'New'), you want a layer of songs and playlists you like, and then a layer of songs you like enough to be listed under 'My Music'.