Plex does alright at suggesting music from your own library, and also has some really nice DJ-like song transitions that are legitimately way better than any other track fades. However, Plex users have been frustrated with the company's slow response to fixing long-standing bugs, and some of the features are paid. It's also not open-source.
No idea if it can suggest music that isn't in your library; I know that they integrate with Tidal though, so maybe if you have that it'll also suggest stuff from Tidal?
I've yet to see artists migrate here. The artists started on DA, Newgrounds, YT, Tumblr, etc. The professionals moved to Twitter.
Reddit started from geek & tech culture, not creatives. Its ability to foster discussion extended well to not just techies but to everyone. Most creatives I've seen shy away from Reddit.