I think the more important point here is that the popular artists supported by big labels become black holes, sucking in all the money. It doesn't matter that you, and all your friends, and all your friends' friends, all listen to the same 3 niche artists day in, day out - approximately all of yours and theirs money will go to some pop artists none of you ever listen to, simply because that's what a much larger general population listens to.
So, it's like 99:1 ratio, but 99 side is Lady Gaga and friends, and 1 is all the indies and niche artist around the world together.
Before streaming with pro-rata royalties, when you bought a record, some money went to the artist of the record (after distribution cuts etc).
Of course Spotify doesn't care. They have to give up 70% of their revenue anyway. But the distribution of this money is the important part and of course pro-rata benefits big labels who have control over the catalog on Spotify and are shareholders.
So, it's like 99:1 ratio, but 99 side is Lady Gaga and friends, and 1 is all the indies and niche artist around the world together.