Not OP, but also used the API for music discovery, crawling the related artists network from playlists I'd created to find highly connected nodes. I found that strategy was very efficient at filling blind spots in major genres I listened to, and reasonably good at exploring random niches, but generally wasn't the place I found songs that felt truly fresh to me. It felt like it got noticeably worse about 5 years ago, when I perceived them to have ramped up the payola, but that might just be in my head.