I think part of what drives the complaint is that a song being on Spotify is much more valuable to the listener than it being on the radio. There's a spectrum of value ranging from the radio at the bottom (you are subject to the whims of the DJ on when and where you hear the song), to Pandora (you still aren't in complete control, but you have a lot of influence), to Spotify (you are in complete control as long as the song remains on Spotify), to owning the song on an album or as a DRM-free download (you are in complete control forever).
I think since Spotify is so much closer to owning an album than it is to radio, many artists expect it to be closer in value to album sales than radio plays.
Not saying ignorance of the proper comparison isn't happening, just that it might not be the only reason.
I think since Spotify is so much closer to owning an album than it is to radio, many artists expect it to be closer in value to album sales than radio plays.
Not saying ignorance of the proper comparison isn't happening, just that it might not be the only reason.