Startups exist in a complex ecosystem of competing forces. This ecosystem changes all the time. Your product and the market are only two of the multiple factors that could influence your startup. Even then, what constitutes your product and how you define your market will also change throughout the course of your startup.
The ideas behind 'product-market' reduce this complexity into an intellectual exercise whose premise that product should fit market for success to happen is too simplistic and inaccurate. Assuming the product-market fit theory and extrapolating to corollary's and model's the kind this article portrays is great for an MBA classroom workshop but little else outside.