It's different because if you imagine Spotify only had 2 users, Alice and Bob, and Alice listens to Indie Band X 10 times a month, and Bob listens to Megastar Y 10,000 times in a month, Y would receive almost all of the artist revenue in the current model, but in the model that GP is proposing, both artists would make the same.

Essentially A's money is going towards Y, even though she never listed to Y.

(I'm not expressing an opinion on which of these I prefer)