This article suggests that machine learning and collaborative filtering are incapable of producing healthy recommendations. I beg to differ, the New York Times may not like the result but they work for the vast majority of users on any service with too much content to manually curate.
YouTube is a _disastrously_ unhealthy recommender system, and they've let it go completely out of control.
It's better to compare Spotify's recommendations to Netflix's recommendations, which also deals with mostly professional content. Those two systems have comparable performance in my opinion.