This is from 18 August, 2015, so it's possible things have changed. But it's interesting anyway, and many links are given.
Most music streaming services have been paying artists on a per-click basis. So most subscribers' money doesn't go to the artists they are listening to, but rather whichever artists get the most clicks. And this system is extremely vulnerable to click fraud.
The author argues that Subscriber Share is a better system. With that method, your subscription fee is divided among the artists you listen to according to the percentage of time you spend listening to them.
FAQ includes additional links and replies to counter-arguments.