Through creating a hypothetical scenario can service developers expand their understanding of the problems which are otherwise difficult to see. The background to a scenario can e.g. come from simulation of personas.
Additional reading
Stickdorn, Marc, and Jakob Schneider. This is service design thinking: Basics, tools, cases. Wiley, 2011.
Cross, Nigel. Engineering design methods: strategies for product design. John Wiley & Sons, 2008.