I know it at least since the 2008 crisis. Google made a choice, manipulate search results /display on page to stop sending as less visitors as possible to non-Google sites.
Perhaps not coincidentally that's about when the fundamentally-a-bad-idea service of Facebook started to get huge as it grew past college campuses, and showed it was really easy—like, incredibly easy—to convince all these new Internet users to give strangers tons of information about themselves, in gross violation of previous Internet norms of avoiding posting personal info anywhere, and that one could make stupid amounts of money by facilitating these poor choices.