> I am making the point that Google effectively benefited from the large amount of human labor...

This is exactly right, but the thing most people miss is that Google has been using human intelligence at massive scale even to this day to improve their search results.

Basically, as people search and navigate the results, Google harvests their clicks, hovers, dwell-time and other browsing behavior to extract critical signals that help it "learn" which pages the users actually found useful for the given query. (Overly simplified: click on a link but click back within a minute to go to the next link -> downrank, but spend more time on that link -> uprank.)

This helps it rank results better and improve search overall, which keeps people coming back and excluding competitors. It's like the web of trust again, except it's clicks of trust, and it's only visible to Google and is a never-ending self-reinforcing flywheel!

And if you look at the infrastructure Google has built to harvest this data, it is so much bigger than the massive index! They harvest data through Chrome, ad tracking, Android, Google Analytics, cookies (for which they built Gmail!), YouTube, Maps and so much more.

So to compete with Google Search, you don't need just a massive index, you also need the extensive web infra footprint to harvest user interactions at massive scale, which means the most popular and widely deployed browser, mobile OS, ad tracking, analytics script, email provider, maps, etc, etc.

This also explains why Google spent so many billions in "traffic acquisition costs" (i.e. payments for being the Search default) every year, because that was a direct driver to both, 1) ad revenue, and 2) maintaining its search quality.

This wasn't really a secret, but it (rightfully) turned out to be a major point in the recent Antitrust trial, which is why the proposed remedies (a TFA mentions) include the sharing of search index and "interaction data."