Comment by pona-a

It is much more complex than an LLM There are thousands of human written rules to efficiently determine a fundamentally subjective ranking order, running on a uniquely large corpus.

Besides search is not a very good business: people are not inclined to pay for search, websites are averse to non-Google search crawlers, ads require an even larger over-investment in a top tier malware development, psychological manipulation, and statistics teams, while the real ad market is actually in a much more dire state than Google would like you to think.