Accountability and inspection of Product Goal

I can't think of a case where the Product Owner would not be the one accountable for the Product Goal. The reason is that I can't think of a case where there's a product or service being delivered that has a single stakeholder. The Product Owner is in the position to understand all of the external stakeholders and make decisions about their perspectives when crafting the Product Goal. The Product Owner is also in a position to work with the other members of the Scrum Team to make sure that the Product Goal is feasible and well-understood.

As far as when you inspect the Product Goal, I can't think of a reason why you wouldn't want to do it at every Sprint Review. One of the outcomes is to adjust the Product Backlog, and the Product Goal is a part of the Product Backlog. Therefore, an outcome of the Sprint Review would be to inspect and, if necessary adapt, the Product Goal. The fact that key stakeholder representatives are invited to the Sprint Review also makes it a good opportunity to inspect the Product Goal.

I'm not sure what you mean by "assess the Product Goal". I believe it's as simple as asking all of the stakeholders if they believe that the Product Goal is still relevant and valid. If anyone has any concerns, the Product Owner can dig deeper to understand if it's just a matter of prioritizing other stakeholders' needs over the concerned stakeholders or if adjustments need to be made to the Product Goal.

I do not mean by that "who is accountable for ensuring the Scrum team delivers the increments as guided by the product goal" but who is actually accountable for crafting the accurate, deliverable, value-generating product goal.

Why would there be a difference? In Scrum, a commitment must be agreed and met by the people who will do the work.

In book terms, it's the product owner.

In the real world, it's the leader of the product vertical (CPO, VP Product, etc.). Tesla is a product. How often have you heard of the product managers at Tesla? You hear about Elon Musk because he is the leader of the product organization which he envisioned and built.

Thank you all for your valuable inputs. 

I agree with most of your responses and the questions you have posed. However, I am sure that there is more to the product goal than meets the eye. 

@Thomas 

The reason is that I can't think of a case where there's a product or service being delivered that has a single stakeholder. 

I agree with this. However, I have seen in an umbrella of product offerings, there are often competing products, and I have seen budgets for misaligned products getting slashed even if the Scrum teams are performing well and delivering the increments consistent with the sprint goal and (even) product goals. It appears that a strong business value alignment must also be present. In that case, I believe the validity of product goals needs to be inspected even outside the Scrum team, of course taking into account the insights from the Scrum teams. 

Secondly, also if we visit the Scrum Artifacts section of the Scrum Guide, it suggests that product backlog is measured against product goal, hence it is my understanding that the product goal is somewhat frozen (at least for a larger time frame than a couple of sprints) otherwise, measuring the progress towards a consistently moving target is not desirable.

In fact, the Scrum Guide goes a step further and sets a benchmark

The Product Goal describes a future state of the product which can serve as a target for the Scrum Team to plan against.

and 

The Product Goal is the long-term objective for the Scrum Team. They must fulfill (or abandon) one objective before taking on the next.

When I say "assess", I refer to this alignment of this future state (product goal) with the overarching business vision of which product is one component. 

@ Ian,

Agreed, that there should not be a difference. But what if the commitment is towards the product goal that does not meet the business vision?

 @Mark,

Definitely, you have a point. From the Tesla example, what if the PO which builds a digital interface sets a goal to develop a product, which is impossible to seamlessly integrate with the mechanical components? While all the POs from different work areas may be collaborating, a common goal must be agreed upon. 

In the past, while I was working in the aviation sector, this issue was quite pertinent, though, at that time, we did not have explicit mention of Product Goal in the Scrum Guide. Sometimes the product goal needs to be set outside the Scrum team to better integrate multiple products in the suite of products. 

My question was through that lens.  

Thanks