The ideal "10x engineer" in my mind is one that helps their team win significantly more often. Competitive swimming is maybe not the best analogy (although I have worked with engineers like that before too). If you want sports, maybe basketball. You've got a good team, but you've got a stellar player that makes them all better.

well to simplify it: if 2 competing companies with 1 programmer each were trying to create $popular_app_or_website then the company with the more productive developer would "win" more often

no, businesses win or lose based on sales & marketing, not how productive their engineers are.