When Spotify sees songs added to playlists it seems to treat that in much the same way as a Like, giving you the best of both worlds - properly curated playlists and a well-trained Spotify. I’ve continued to use that playlist to add songs I like from a variety of genres, while also building more genre-specific playlists.
Years ago, before the Like button was introduced, Spotify had a star button, which used to add that song or album to a playlist called Starred.
