I believe surveilling readers is lucrative, but I can’t get a clear picture of exactly how lucrative.

I get that there isn’t much overhead associated with accepting money to take code someone else wrote and put it on your site, but I don’t know what the economics are for that sort of thing. Also, behind the layers and layers of intermediaries in the ad and marketing tech world, who’s the actual customer for publishers, and aren’t publishers minor players in fueling this business when compared to social networks?

(Excellent piece, btw.)