Clarify what the primary function of the Product Owner role is to avoid unconscious proxies

Clarify: "The Product Owner is responsible for maximizing the value of the product and the work of the Development Team."

This sentence appears to skim over the primary function of the PO role in six words combined with a secondary, more tactical concern that mixes messages.

Suggest: "The Product Owner is a business decision making role responsible for maximizing the value of the product being developed using Scrum. At a tactical level, the Product Owner may seek to maximise the value of the Development Team's work on a Sprint-to-Sprint basis, but not at the expense of optimising the value of the overall product."

Rationale:
Interpretations of the Product Owner role vary widely and these varied interpretations have become more stark and codified over the last few years.

Interpretation A: the PO role is primarily a commercial decision maker who takes responsibility for maximising ROI of the product overall. This involves deciding the content of the product and the timing of its release. Given interpretation A, it is common for the business person with the greatest stake in the product/initiative to play the PO role and delegate detailed clarification work to the development team and business people closest to the relevant detail.

When more than one development team is developing a product interpretation A suggests that there be one overall PO for one overall product.

Interpretation B: the Product Owner role is primarily an analyst who leads the refinement of backlog for a single team and orders the team's refined backlog (often within the context of an set of priorities previously agreed with stakeholders).

Where more than one development team is developing a product, interpretation B suggests that there is a PO per team and decisions across the product as a whole are made by other means (often by means outside of the Scrum implementation). Given interpretation B in an internal IT systems development environment it is common for Business Analysts from the IT department to be appointed PO's and handle most or all of the detailed clarification themselves.

Interpretation B typically results in a proxy/fake Product Owner rather than a decision maker with genuine authority. Whilst a good deal has been written about this issue elsewhere (e.g. https://kenschwaber.wordpress.com/2011/01/31/product-owners-not-proxies/ ) the Scrum Guide says little to explicitly discourage this interpretation.

In a multi-team context, multiple individuals optimising their own team backlogs is likely to result in local optimisations at the expense of optimising the whole product (see Systems Thinking) unless this is performed whilst considering the whole.