Yeah, I've been struck by this possibility while reading a lot of the rebuttals here. "Targeted ads work because otherwise why would they be so prevalent?" or "targeted ads work because x, y and z." There could be a kind of meta-advertising at work here, where adtech is often actually marketing towards the ad market itself. Would that mean it works? In a way--clearly lots of people are buying into it. And people wouldn't necessarily notice the scheme, because after all even if targeting isn't as effective as they claim it's still a form of advertisement and would generate some sales as dumb ads regardless of whether the targeting is really effective. We'd have to measure how much above that baseline the ads are driving actual sales somehow.

But I've yet to see some actual controlled evidence showing clear data in terms of sales that we can be reasonably sure were generated by targeted advertising. I think such evidence probably does exist, I'm not saying I don't believe it just yet. But all the arguments here seem to confuse science with scientism--what we have is a lot of reasoning and academic explanations of how people think it works, which is just not the same as evidence. It doesn't matter if something sounds like the way it might work in real life, we have to make observations to call something data. I haven't seen much data here.