I wonder what they would say too ;) Honestly though: I am not at all opposed to measurable objectives / OKRs. I just think that elevating one metric to the level of North Star Metric comes with certain risks.
With the OKR framework, each team will typically have 1–4 objectives with 2–4 key results each—far from one north star metric.
Regarding the ownership: I completely agree. I have also worked in organizations with an overarching strategic goal. At Yammer, we had the goal to increase the number of highly active groups to a certain number over the course of a year or so. This was, like the north star metrics described, influenced by a lot of factors from sales to product, so the lack of clear ownership was definitely there. However, we didn’t use this metric to “measure the success of the product team”, nor did we call this our north star—it was a clear strategic goal, but temporary and not the sole measure of our success.