Why is using an undefined user as the 'who' in a user story problematic?

Using an undefined user as the 'who' in a user story is problematic primarily because the intention of the user cannot be clearly defined. In user-centered design, understanding the user's specific needs, goals, and behaviors is crucial to creating effective solutions. When the user is not well-defined, the team lacks important context about who the user is, what problems they face, and how they interact with the system. This ambiguity makes it difficult to write focused and relevant user stories, leading to vague requirements that can result in a product that does not fully meet the needs of the target audience.

When user stories are crafted with a specific user in mind, they can better guide the development process and ensure that the final product aligns with real user needs. Clear user definitions help in forming accurate acceptance criteria, condensing feedback, and ensuring that the design is user-centered.