I would say that the US rejected both the Treaty of Versailles and league of nations, and the American contribution to post WW1 Germany couldn't undo the billio

I would say that the US rejected both the Treaty of Versailles and league of nations, and the American contribution to post WW1 Germany couldn't undo the billions in reparations that Germany was compelled to pay after the war. The whole point of the Marshall plan was to rehabilitate their economies under representative governments - it would have failed equally badly after WW2 had the same crippling punishments been applied as after WW1. We have tried propping up governments and economies since, and many of the efforts have failed because the governments were either corrupt or unable to foster a culture of peaceful representation of the populace- evidence in support of the point we both agree on, at least, that the Marshall plan didn't succeed in a vacuum.