I’m surprised the YC application hasn’t been more of a focus in this discussion. The following questions are pulled from the application (perhaps an older version): What is your company going to make? Why did you pick this idea to work on? Do you have domain expertise in this area? How do you know people need what you're making? What's new about what you're making? What substitutes do people resort to because it does…
you miss what PG was stating, Audience and User is the balance sheet and the business plan nothing else matters.
Now, we can talk all day about whether that is a healthy path, to constantly drive to build Y/VC-level growth no matter what. But whether or not you buy into the "startup" lifestyle, YC absolutely does run under that model, so they seek people who match, and those people aren't identified by snazzy spreadsheets.