You've told me nothing I don't already know. Americans suck at the marathon, as a rule. Rupp, Hall, Meb, and Deena have been exceptions to that rule since 2000. Even Rupp wasn't good enough to get the AR that Mantz did, and Rupp's marathon medal was due in large part to super shoes that only Kipchoge had at that time. Jerry Lawson ran 2:09:35 in 1997, of course at least a couple of unknowns who are built for it could run a couple minutes faster than that nearly 30 years later. You're only surprised if you're ignorant.