Now I haven't checked if those bands are sharing free promotional material on Bandcamp, SoundCloud, etc. but something feels a bit iffy about this.
I'd be a lot happier if the artists featured were clearly releasing music under Creative Commons or something like that. Right now this makes me think that if I use it the music streamed would be against the artists' wishes.
Just like with software, FOSS is better for everyone than just pirating commercial software.