Yeah, there are indeed those who say that, and I'm not one to pooh-pooh the idea out of hand.
The fact remains that the Americas, particular North America, has been struck by impacts of space debris (including large offshore impacts like the Eltanin impact) more than the rest of the Earth's landmasses during the past two million years, and buried in ice blitzkriegs. The Meteor Crater impact probably wiped out earlier fauna as well as all or most humans who were already around.
Regardless, the Americas have never been starkly isolated from the rest of the Earth, unlike what the biased claim.
Bring back Pangea! 😊👍