I hope someone can provide a meaningful answer as regards to the US army doctrine. In the meantime, people have asked about the legitimacy of these quotes before: they're probably apocryphal.

While more could be said about this, particularly how cultures create narratives about groups they are envious of or otherwise resent as a way of establishing national identities in term of perceived traits, u/Nubz9000 does a good job of describing American WWII military doctrine relevant to this historiography in his response to a question about the distinctiveness of period American small arms here.