Careful ... not everyone bases or dismisses their long-held beliefs on "observed reality".
What many seem to under-value is that D'Amato retired and didn't compete for several years. We cannot equate her with athletes at the tail end of 20 years of continuous competition.
For comparison, I was looking at Irina Mikitenko's performances. For 10 years, she was a 2:24 runner, and then in 2008, produced a 2:19:19 at 36 years of age, followed by a couple of 2:22's over the next years, one at the age of 39. I don't find that progression particularly unusual, especially considering that women's marathons tend to be tactical, rather than time trials, and a five minute difference can be explained by race day conditions and race tactics.
More than one elite coach has told us of the need for 7-10 years to build your "aerobic house". Coaches from Lydiard to Canova have said something similar.
Now, factor in the new shoes that give 4% improved efficiency, and D'Amato's American record is not anything that should be particularly unexpected 10-15 years after Kastor and Mikitenko. If a 2:2x runner, is running 3:49 and 3:10, we should expect massive improvements some years after the day she decides to train and race to her potential.