People often think of Lean Startup as the only possible methodology for product development, but that’s just because it’s the most popular one.
In reality, there are other, equally valid methodologies:
At the end of the day, what all these methodologies have in common is that they give you a structured framework to cheaply iterate through the space of all possible ideas and find the optimal one–it’s the prime example of how building experimentation guidelines gives you structure-driven-freedom.