Making repeated prototypes (in est, experiments), quickly, is how you approach entrepreneurialism in any sort of scientific manner. Nothing needs to scale, or work at the edge-cases, until it has product-market fit; and you might need to write twelve or twenty or two-hundred different apps until you find one that works out that way.

That's what makes these frameworks popular with HN: startup founders are not in the business of executing on a known business model (which might be viably accomplished even through a waterfall process and code written in C); rather, we're in the business of searching for a business model by building MVP after MVP, as quickly as we can.

MVPs don't need to be able to be evolved into stable, well-engineered products. They just need to prove product-market fit. Once you've got your traction, your proof, your intent-to-buy, you can use that to get the loans or capital, to hire the talent, to build the Well-Engineered Version. Until then, "engineering" is not even a consideration.