I'm not sure about spotify, but I have seen this problem with Netflix: I'm an adult paying full for my Netflix subscription and for that price I would love to have a few great and expensive movies every month for my age group.

But what I usually see is lots of movies made for teens who are binge watching Netflix even though they are paying the same. Netflix has some public presentations on their algorithm and from the presentations it looks like they are optimizing for watches without weighting by subscription revenue per watch.