The only thing I ever see are people comparing against the money that 90's rockstars used to be able to bring in from album sales.
That ship sailed a long time ago, Spotify take everyone's money, substract a percentage for themselves and distribute the rest based upon number of plays.
If you were a big artist it's probably worse because you aren't getting a sweet deal to pull you onto a label (which we would then have you bitching about in the music press every week), or your a smaller artist and don't make much off it because you don't get the plays but you would have never seen the big money from tape/CD sales anyway.
I've also seen people argue that they never see the sort of money that they would get with a single play from BBC Radio, completely misunderstanding that BBC radio would probably never play their song, there is a much smaller bandwidth for playing music. Per person listening to your song, it works out not far off a play on Radio 6.