Yup, I worked on the playlisting service for a little while at Rdio, it was pretty simple but worked well. Based on those presets we would decide how far along the artist similarity graph we would walk from the original playlist "seeds".

Would you please stop reminding me how much better Rdio was :(

Nobody understands when I complain about losing Rdio (which is often), it was sooooo much better and nobody knew/cared.

Tell me about it. A large part of the community we had at rdio used to meet at in a post-rdio slack channel after the service went down. For months we discussed alternatives and how mediocre and barebones they were compared to rdio. Most of them, including me, settled for Spotify, but the community is pretty much gone.

On the other it led me to double down on my purchased offline music collection, which I already maintained long before rdio.