Even more egregiously, maybe sometimes the advertiser's metrics have some reverse-causality: you buy the camera, then they show you the ads for it; but something in their metrics isn't properly modeling the sequence of events (e.g. they correlate retargeted camera ads shown per week with camera sales per week). Then they mistakenly take credit for a sale that happened before the ad was shown.
That's not to say such mistakes always happen, but I wouldn't be surprised they didn't happen fairly frequently. Given that measurement is hard and both adtech and advertisers are motivated to present success stories, and may not be too motivated to second-guess positive-sounding numbers.
I can't even imagine the outrage that would happen if it emerged that Google was using its access to people's emails to measure ad effectiveness.
Incidentally, those weren't targeted ads. Those were ads hand-picked by the person producing the content about those books. From that very small sample I conclude that ads relevant to the context in which they're placed are more effective than targeted ads.
I will say that I'm thankful that Squarespace, Audible, and Skillshare support independent video and podcast creators. I click their referral links sometimes to check out new features etc, but would only ever sign up if I needed that particular service. Still, I think that form of repetition helps their mindshare in a positive way.
I did buy the Glif directly from an ad on Daring Fireball, albeit months later, and in combination with brand awareness from their free time-lapse / speed ramping app.
This is annoying and, when one thinks about the implication that everyone and their dog knows who you are, scary.
I have never bought off of ads otherwise and find that most of the time they are not relevant to my interests. I also started using an adblocker because of other reasons (mal-ads/autoplay) even though I previously did not do so because I felt text/banner ads were quite acceptable in order to help keep the lights on.
I was researching cameras. I saw very little camera ads in my research. After I bought a camera? Ads for the camera I just bought everywhere, for months afterwards. I have not once clicked on a ad and bought something. I maybe clicked on 10 ads in my lifetime and they were 75% stuff I THOUGHT I had no intrest in. I think targeted ads is the biggest con no of our age.