Interesting read, it's a good concept to measure on impact and the unique contribution that person has made.

With the examples of what isn't impact, for example hiring 10 people. How can this not be impactful? If the person has spent a lot of time and carefully hired 10 people that have then joined and delivered their own impacts then hasn't the original designer also delivered their own unique impact by being diligent to the hiring process and putting the time into it?

Just a thought that the impact doesn't necessarily have to come from the center point of origin but can happen indirectly throughout the organisation - which makes it harder to measure I suppose!