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 paperclip maximizer (where paperclips correspond to eyeball-hours spent watching YouTube) and at some point optimizing paperclips becomes orthogonal to human existence, and then anticorrelated with it.
I think it's a perfectly fair thing to say that maybe the negatives outweigh the positives at the present.
(This argument doesn't apply solely to YouTube, of course)