Google's golden goose is their tracking. Between their ad networks, Android, and Chrome, and their own search engine, they know every single page that most people view. They can then use that data to work out what to display for searches.

The reason that Google Search punishes slow loading sites, as proven by the AMP 'nice comparative boost' controversy, is because most of the time a page loads slowly is because it has multiple ad network trackers on it. Google will do anything to stop a page from doing that. The good news is this stuff is already being called out for anti-trust issues.