There's a 1000-year gap from Moroni to Columbus. Much can change during a millennium, for example scientists have examined what would happen
if people suddenly disappeared, and how quickly nature would consume man-made cities. Have you seen
this series? Now let us suppose that in America's 1000-year gap, God gave nature a head start through a combination of man pillaging every person, place and thing via war, and God "destroying" other communities via natural disasters.
God has said that he will have a faithful people, and you all know
Hebrews 11:1.