When I say we could have avoided fighting Hitler, I don't mean we could have avoided naval clashes, given that Hitler's declaration of war was the beginning of unrestricted submarine warfare against American shipping. I mean we could have avoided landing troops and equipment in North Africa and Europe and sending wave of wave of bombers over Europe (~50% death rates out of all aircrews that served), which accounted for the vast majority of the 300K dead we lost in the North African and European theaters. The rationale for staying out except when directly attacked would be the same as our rationale for not intervening during the Napoleonic Wars and various other 19th century European conflicts.