And they certainly help Yee who can quickly specify which ones he wants to send the photos of his son to and which ones will get his latest insights into the most effective approach to productdevelopment.
Validating a hypothesis around whether or not a customer will find any value in your product, and iterating until you find the right product-market fit, is an approach that should extend well beyond the productdevelopment stage.
Feature Driven Development, another popular approach, contrasts with Scrum by defining the main features that a software product must have, prioritising them and then working doggedly through the list.