It's not really about the $3 to the artist. Spotify gets value from having all that material in their inventory, and doesn't pay anyone for it, and it wasn't a natural resource that they harvested, someone had to create it.
Actually worse, they say they do pay someone for it, they spread it among the other creators who they ARE paying.
You could try to think up ways to rationalize it like "publishing fee", but I don't see any reason why anyone should.
