The chestnut tree used to be a major food source for wildlife and people. Since it flowered later than most trees it was not caught by late frosts. But, most of us, except maybe Armybrat, have never seen one mature enough to produce chestnuts. Like several other introduced, invasive critters and diseases it happened by accident.
https://en.wikipedia.org/wiki/Chestnut_blight
But, it didn't get all of them. That's the thing about diseases. A few lucky individuals will have some genetic resistance. We know that now about the Black Death. You either had the pair of genes with full resistance and didn't get sick, one of the pair and kinda got sick, but survived or none at all and you were a goner. The same thing applies to other living things. Well, somebody has been diligently working to find the resistant survivors of the Ozark species of chestnut and then select the most resistant ones for reintroduction. I think it can work.
A legendary Ozark chestnut tree, thought extinct, is rediscovered, Nat Geo 6/24/19