So it could start with someone writing down how a feature should work, then some designers creating some mock ups based on the discussion. Finally programmers can look at the description and the Figma designs and start implementing, with all the context still available. And since the document is created from the start, the entire team can start commenting throughout the whole process rather than at the very end when the jira ticket is created. It helps avoid stuff like this[1].
I obviously like it, but I am biased :).
[1] https://cutlefish.substack.com/p/tbm-1052-what-didnt-end-up-...