Google themselves also suffer a lot from bad actors. Many people start installing ad blockers after visiting abusive sites, and these ad blockers block the more tolerable Google ads as a collateral. For that reason, they want to introduce a built-in ad blocker in Chrome, and unsurprisingly, given their position, they are taking a lot of precautions.
It's the biggest one, followed by company specific recommendation engines.
Usage stats could help you improve a user interface, teach users new skills (eg: "you always do this, here's a shortcut to save you time"), perhaps more personalized operating system interfaces and defaults.
You probably don't need a fancy pseudo "AI" system for any of these, but that's the current gold rush so someone's gonna do it