The thing is that this has actually been disproven by Gregory clark, in his study of long trends in the english economy, were he shows macroeconomic indicators have no correlation to institutions. Or changes in institutions. The answer he comes up with is equally absurd, but that's another topic.

And by Robert Allen, who showed in a recent paper that migration and wages were process that regulated each other in European colonies. The higher agricultural productivity the higher wages and the more migration, Mexico had lower agricultural productivity given early modern tech and so it was poorer, since it received less migration, Spain was also poorer. So essentially since the yanks exterminated the natives there was a lot more land for yeoman farmers in the us than in Mexico.

That being said the great M. M. Postan published a series of articles 70 years ago were he shows how these theories don't fit the historical record. Institutions matter much less than changes in the technique of production, wich historically are driven by demographics.