I think the key point of the book is that unless there is a massive transfer of people from place to place the power of historical institutions can carry over generations and generations.
Is quality of institutions the one truth to explain it all? No, but I find it pretty hard to argue against that it is a relevant factor in historical evolution of polities regarding their quality of administration and general expectations of life outcomes of their populations.
My intent was not to sell the book as "the one truth", sorry.
You can talk about the legacy of the colonial institutions in the respective countries, but that has little to do with how hard South Korea worked in the 1950s, and more to do with how Japan and England administered their colonies, and how the transition from colony to state happened.
They're interesting books for sure, I remember enjoying reading them. But they're very selective in the facts they tell and how they tell them, and so they're almost worse than fiction in that respect.
I agree with what you wrote in general.
Why I find other explanations more worthwhile - which you opened up above - than "US helped them" is that is quite critical for countries to be able to advance economically. Based on several examples I don't think it can be explained simply by having a wealthy external sponsor. Hence it would be more important to focus on the things that made this thing happen, in order to understand if something could be replicated.
As an example of potentially replicable factors, for instance land reform seems to be a thing that has been at the roots of economic advancement of several countries. (Finland, South Korea). Of course, it can be screwed up as well (Zimbabwe).
I agree books that try to simplify things are dangerous, but really entertaining when they structure their thesis around solid facts. I don't think anyone has "the final truth" so an author that has at least tried to put forward an explicit thesis is always a worthwhile read - a clearly stated thesis is something the reader is then able to clearly refuse.