<blockquote>The “surveillance business model” of building up detailed electronic dossiers on internet users in order to predict what they want to buy and how to sell it to them produced some genuinely impressive results in its early years. The serendipity of seeing an ad for something you had been thinking about proved very powerful in the early days of Facebook and the first generation of “retargeting” services.

But a look at Facebook’s ad-card rates shows that the novelty of this technique wears off fast. Facebook was founded on the premise that it could use its mounting dossier on your behavior to figure out how to sell you things faster than your natural defenses would repel its pitches. If that ideology was borne out, you’d expect to see the company’s cost-per-thousand ad rates climbing into the stratosphere. Instead, they’re damned close to the rate you’ll pay for regular, minimally targeted display advertising elsewhere.</blockquote>