I love this.

Maybe these are incompatible desires, but I would really like some kind of system that allows me to own and present my own music listening data while also allowing me to interoperate with a broader music listening culture.

Newsletters and blogs are great for discovery, but I also really value the way my last.fm has allowed me to recall a band I used to listen to a decade ago because I can remember a few of their contemporaries that are neighbours in the Similar Artists graph.

Do you mean something like last.fm with their API [0]? Or did you have something more in mind?

[0] https://www.last.fm/api