It was a long time ago that I read a history on this, and I might be missing a detail, but the gist was Google's investors were clamoring for profits following the .com crash and Google realized the data they had was a gold mine if they could just figure out how to apply ML to it.

They tried really hard and did okay for a while using it for advertising, but Doubleclick did it better, so they bought it in 2008.

AI (ML) was absolutely on the radar.