The reason that I'd never use YT Music is that I never trust anything from Google: their interfaces are ugly, everything's user-unfriendly, and they have the habit of discontinuing a service at any time. Also it has the impression of not really being well-thought as a product: why name a music service after a video service? I know it's not the case but it always reminds me of those low quality music playlists where people collected low quality unofficial music videos back then in YT just for the music: simply not the right tool for the job.