Google bet the farm on their ability to do just that though. PageRank and other technologies where suppose to suppress content farms that just aggregate the same content over multiple sites for ad revenue,
I have not done SEO in a long time but back in the day (early 00's) that was a sure fire way to get your site demoted in the google ranking was to have content 90+% similar to another site. It was a big problem for ecommerce sites that sold the same products as the larger sites because often they would just use the same product description from the manufacturer
they didn't "bet the farm" on that at all, they've been desperately trying to diversify out of search advertising for basically the life of the company. Of course, they haven't succeeded but not because they're relying on search ads.
I have not done SEO in a long time but back in the day (early 00's) that was a sure fire way to get your site demoted in the google ranking was to have content 90+% similar to another site. It was a big problem for ecommerce sites that sold the same products as the larger sites because often they would just use the same product description from the manufacturer