Nice article David indeed. I agree with you in full. I will add a minor observation - when we teach Scrum, we have mostly in mind a single team and there is one Product Owner. We see PO as a single person. But in real environment PO can be more people. Still no problem, but usually organizations tent to label the head PO, the one that deals with strategic issues as Product Manager, and those others who deals with communicating to teams (operational issues) remains Product Owners.

I will also add that as a PO you always own something (that is why Owner), problem, budget, etc. This is the role about, to own something. If I inspect agile adoption and I find out PO do not own anything, I can shortly expect many problems as PO as a messenger or just administrator is not able to deliver any value.