Gregory's Server
@liaizon depends on when you used it. I quit in January 2016. Before then, I've never ever gave the music section to anyone and did everything there myself. Actually, I still use a custom build of the VK app to, among other things, listen to music for free lol.
I thought about it in Smithereen, of course I did. The system needs to be rock-solid against copyright holders, and that ain't easy. WebTorrent is promising. DHT might work for global search. All this needs further exploration.
@grishka Used it every day while I was traveling in Kazakhstan and Kyrgyzstan for two months. And yeah was only using it through an Android phone that whole time, mostly for people to recommend music for me to listen to. Have you played with Funkwhale? It might be cool to be able to just subscribe to a #Funkwhale library through #Smithereen and then you wouldn't have to deal with the uploading and managing of tracks, just the player part since they are focused on the other side.