What Google knows about you, or Facebook for the matter or any other buyer, can be used for targeting and as user features in the ML model which is used to determine the price the buyer is willing to pay for a given impression in the auction.
Most advanced buyers with actual ML in their buying algorithms do this. But ML works in statistical averages on the behavior seen across all users visiting a particular site. At that point the buying process works by figuring out the expected value of a new impression and bids that value, the expected value depends on how the advertiser values clicks or conversions or impressions, so as long as the cost of the impression is lower than the marginal value an algorithm will continue to bid, and potentially win, because it's worth it.
And you can do all the A/B tests you want and you'll see that this is actually true, capping frequency. or choosing to not show an ad because the position on the site is not great, is not a good idea, the right process is to determine a price that, all things considered, is the maximum price (proxy for value and risk) you are willing to pay to be shown in that bad slot that adds marginal value for the advertiser, and marginal value is measured however the advertiser wants.
Most advanced buyers with actual ML in their buying algorithms do this. But ML works in statistical averages on the behavior seen across all users visiting a particular site. At that point the buying process works by figuring out the expected value of a new impression and bids that value, the expected value depends on how the advertiser values clicks or conversions or impressions, so as long as the cost of the impression is lower than the marginal value an algorithm will continue to bid, and potentially win, because it's worth it.
And you can do all the A/B tests you want and you'll see that this is actually true, capping frequency. or choosing to not show an ad because the position on the site is not great, is not a good idea, the right process is to determine a price that, all things considered, is the maximum price (proxy for value and risk) you are willing to pay to be shown in that bad slot that adds marginal value for the advertiser, and marginal value is measured however the advertiser wants.