You could have the best of both worlds with a Jellyfin server?
I was a latecomer to Spotify and now I can't go back. I've discovered more great music via it than I would ever have imagined. No it's not perfect, but still beats the old way of doing it manually.
This is where the *arrs come in. Specifically Lidarr [0].
EDIT: it's not the exact same experience, but it's better than manual management.
As others mentioned, Lidarr helps with this.
I do have some songs I'd like to ensure perpetual availability, but they're few in number enough that I may go buy them separately, but still use Spotify as my main consumption medium.
I've also found that I'm able to both discover and listen to songs in some genres via Spotify that I've historically found difficult to acquire anywhere else.