In 1945, American economists had been called on to give advice to the utterly destroyed nations of Japan and Germany. Judging by the post-war success of these two economies, their advice must have been superb. This was the last generation of economists trained before economics came to be considered a science. Reducing everything to numbers means that such economists can only track the flow of money, or other symbols for wealth such as stocks and bonds. This assumption is flawed because the real economy moves at a much slower pace.
Folks can take years to make major buying decisions like a house or car.
Moving factories requires months or years of planning. Most importantly, the ability to invent and build the nuts and bolts of the industrial infrastructure takes generations to develop. For example, Germany was unified by Bismarck in 1870 and a conscious social decision was made that Germany should overtake England in industrial capacity. World War I in 1914 to pull even. Because of the destruction of two wars, Germany's absolute superiority in European industrial capacity did not clearly emerge until around 1960.