It is unrealistic to suggest that there is no place for third party experts in a collecting field. If everyone had to be an expert before starting a collection there'd be about 10 collectors in the world because the vast majority of people simply would not devote the time and resources to learning in advance of buying that first item. As is the case with many things in life, many people do not have the time to become expert-level at autographs but still would like to own an item signed by a childhood hero or other meaningful figure, so there is a place for an authenticator in the collecting world.
There is no way that an authenticator will get it right every time--no human ever does. What I take away from the article as the troubling conclusion--if true--is that JSA did not fairly analyze the items in question.
As for false negatives and false positives, I am more comfortable with an expert who says he can't tell from time to time because autographs ain't manufactured items--they vary widely depending on the situation. I've shown these before but it bears repeating here: I got the first of these Lewis autographs in person, a friend got the second one at a different event:
I seriously doubt that an authenticator could deem them both genuine but they are.