Tim Wu in The New Yorker, posits that Netflix's secret algorithm is a human:

Perhaps what we are seeing here is better explained by the rise of a different kind of talent. It is a form of curation ... whose aim is guessing not simply what will attract viewers but what will attract fans—people who will get excited enough to spread the word. Data may help, but what may matter more is a sense of what appeals to the hearts of obsessive people, and who can deliver that. And what that suggests is that competition will remain possible for companies that aren’t Amazon or Netflix, without massive piles of data on hand. It might be enough to know just which cults to bet on.