I agree that it shouldn't be called the most powerful, but there's an insignificant difference between the top 20-30 countries on this list which makes it rather meaningless (IMO) to compare between them. Some random country that few people actually visit might open up visa-free travel to some on the list which will shoot them up a few places.

Anyways, I like the Nationality index (https://en.wikipedia.org/wiki/The_Quality_of_Nationality_Ind...) which takes into account freedom-of-movement with economic and quality-of-life factors, so it isn't just a count of visa-free travel agreements. This seems like a better measure of the power or value of a specific citizenship.