It would be so easy to place ads based on page contents and not based on retargeting. It would be such a breath of fresh air. You wouldn't need to know anything about the person visiting the page. You can still do programmatic ads with competitive bidding. And even according to Double click study, you would make about fifty five percent (iirc) of what you would make with all this invasive tracking.

It would be a win win for everyone.

In an alternate reality where tracking was 100% illegal all the time, would the ad revenue come closer to say 90%, with perhaps 10% choosing another medium altogether? These studies by ad companies seem to always presume their own perfect world where everything else remains just as it is.

Mostly, although some text analysis would need to be done to prevent this:

    (people commenting about how a bad design choice in ACorp's flagship product AProduct led to the tragic death of ten labradoodle puppies.)

    AD: Buy two AProduct, get one free — limited time offer! Woof! ACorp — your pup will love it!

You mean, like how Google ads were back in the beginning?