In the same way that your small time artist is getting some of Taylor swift fans money. In the end the artists still get paid the same under either system.
If payed by total listens Taylor gets 99%.
Now if those 99 listens are from the one user and the other from the other user. Paying by listens ratio per user, Taylor will get 50%.
Over the entire population of Spotify listeners you are going to have high and low listen count users that average out.