Actually understanding those numbers is kind of like product development: you would think it is table stakes, but a surprising number of startups completely fail at it, so FizzBuzz tests like "Can you ship anything?" and "Can you invest $1,000 and have at least $1,000 of revenue?" actually provide useful signal.

"Shipping a product; customers use it; at least one customer acquisition channel works in principle" is actually fairly fall along on the derisking/valuation/etc timeline.