Google had a brilliant advertising business with AdWords originally, where the ads were simply based on the search term and not a bunch of Orwellian surveillance on the person searching. From the research I've seen, all this privacy-invading crap doesn't even improve ad performance much - it's small incremental gains at best. And per this article, those gains are clearly coming at the expense of user trust and goodwi…
Short version. It works really well. Like absurdly well.
Massive fear if browsers started limited cookies. As that would destroy the cash cow.