Original Text: The Planning Process: 2
It would be a good idea for PRINCE2 to heed its own advice by displaying a "product-based flow diagram" such as that advocated under "Product-based Planning". It would be better still if it also showed how responsibility for the various document products flowed between the different levels of responsibility for the project. Then considerable simplification might be found possible.
This is a nonsense statement. PBP does not show responsibilities.
I think it might help if it did.
Now you're just trying to modify the method. A network plan doesn't show responsibilities, why should Product-based Planning? Each sub-process has a section on Responsibilities that shows what you are looking for. If we were to add these to the diagrams, before you know it the method would be accused of being too complicated.
17. PRINCE2, p293