[hakfoo]

I feel like the specific case of "sofas forever" is because of a clear lack of feedback channels.

If you buy a sofa, especially at a different vendor, it doesn't send a signal back to the ad network which could be used to deprioritized the sofa ads.

There's also no trust in the advertiser relationship, so you couldn't just have an "already bought/don't show anymore" button because people would either ignore it or insist they bought everything in the hopes of poisoning data or suppressing ads.