Today [...] bandwidth constraints are largely considered a thing of the past, and recommender systems are no longer commonly framed as techniques for optimizing the bandwidth of a computer network. When people suggest that recommender systems are necessary to manage an overwhelming amount of information, they are not making a claim about digital computers. It would be technically easy, for instance, for Facebook to simply present every update from a user's friends in chronological order. The problem with this much-requested feature, Facebook suggests, is human bandwidth: users would be overwhelmed.