Facebook already harvests some data from WhatsApp. Without Koum at the helm, it’s possible that could increase—a move that wouldn’t be out of character for the social network, considering that the company’s entire business model hinges on targeted advertising around personal data.

So it’s not surprising that Facebook is so coy about explaining why a certain user on its platform is seeing a specific advert. Because if the huge surveillance operation underpinning the algorithmic decision to serve a particular ad was made clear, the person seeing it might feel manipulated. And then they would probably be less inclined to look favorably upon the brand they were being urged to buy. Or the political opinion they were being pushed to form. And Facebook’s ad tech business stands to suffer.

Take Facebook, for example. CEO Mark Zuckerberg will stand onstage at F8 and wax poetic about the beauty of connecting billions of people across the globe, while at the same time patenting technologies to determine users' social classes and enable discrimination in the lending process, and allowing housing advertisers to exclude racial and ethnic groups or families with women and children from their listings.