It's been twenty years. People would have moved on to new jobs, and spread the word with them. Some would have applied for jobs there. After all, non-googlers know a thing or two about their infrastructure, despite being mostly a trade secret.

If nothing else, apparently there are enough of disciples out there that it would be a great way of hiring the right people.

You'd have to believe there is some sort of cabal, completely bent on keeping this enormous advantage to themselves in absolute secrecy, to argue that it is a software development success story.