The one thing that bothers me about Lidarr is that it is album based, not song based. Before streaming services, I managed my local music library with albums as well, but my habits have changed. I basically only listen to my "Liked Songs" playlist on Spotify, and really only have a select few albums that I listen to on the whole.
I tried syncing Lidarr with my Spotify account, but 95% of the downloads then where songs that I didn't care for.
I don’t think there are more than 4-5 albums in my Spotify library where I like more than one songs of it. Or even artists (though there might be more music from single artists). I also just listen by playlists and often just my “Liked” or “all songs”.