Basically this, but it even goes a level deeper. Facebook engineers to not know they are working at the Weekly World News. At a high-level the algorithms treat the actual content as a black box; what matters is how people respond to and interact with that lump of content and this response is what is measured and optimized. A human editor in a newsroom at least applies some conscious thought to the nature of the story and the facts claimed within. The people designing and operating the paperclip/engagement-maximizer do not really try to understand what they are maximizing other than the fact that it is considered a revenue-generating target and their paperclip production gets published in the quarterly reports.