Here's a summary of the entire debate over Book of Mormon geography in one graphic. People accept one assumption or the other, and then confirm their biases accordingly.
It's very simple.by every prophet/apostle who has addressed the topic of Cumorah. But Oliver takes the blame/credit for putting it into print (even though historical evidence shows Joseph taught it even before he got the plates, which he could only have learned from Moroni.)
BTW, this is part of a presentation that I did recently which will be included in the online conference that starts today.