It seems like yet another example of Google making bad business decisions.

Sometimes, those bad decisions can be traced back to people wanting to "show impact" so that they can get promoted. That's often why they do something ridiculous like launch yet another chat app, which they end up killing a few years later.

In this case, it could be something like that (like someone has an objective to reduce the number of people using ad blockers from X% to Y% and will hit that target no matter how much it fucks things up). Or, it could just be that Google has some kind of weird strategic goal in mind that they're willing to burn many bridges to hit.

What's interesting to me is the role antitrust is playing in this. I'm guessing that a lot of the things they'd like to do are things they feel they can't do because it will get the attention of antitrust regulators. Like, they could just start perma-banning people based on cookies and IP addresses, but people might raise a real stink about that. So, instead, they're going with just trying to annoy people enough that they give up and turn off their ad blockers.