> If this were true, then there would exist no search engines consistently capable of finding content highly relevant to the user's query -- as opposed to just returning promoted content, which according to your premise is always winning the adversarial battle.

I can’t tell if you agree that google doesn’t return highly relevant content or if you just get better results than I do. Almost all my search results are dominated by low relevance high click through brands, regardless of quality. For example: quora often replaces high quality content with low quality paywalled answers researched from wikpedia or other public resources. 10 years ago you would have gotten metafilter, which is (imho) objectively a higher quality source less hostile to web users.