Why is it detrimental to use an undefined user for a user story?

Using an undefined user for a user story is detrimental primarily because the intention of the user can't be clearly defined. User stories are crafted to encapsulate the needs, goals, and motivations of a specific user or user persona. When the user is undefined, it leads to ambiguity regarding their needs and priorities. This lack of clarity can result in deliverables that do not resonate with actual user requirements or use cases, making it challenging to create effective solutions.

Moreover, without a well-defined user, teams may struggle to identify the appropriate acceptance criteria, which are essential for determining when a story is complete and meets the needs of the specified user. Defining the user persona allows for a more focused and efficient development process, ensuring that the end product aligns closely with user expectations and enhances the overall user experience.