This is the classic "blame the parents" explanation (see refrigerator mothers: http://www.autism-watch.org/causes/rm.shtml). It frequently gets the causality backwards: the kids don't act that way because of their parents, rather the parents act that way because of the kids.

The vast majority of parents don't want a diagnosis so they can blame it on the disease and ignore their responsibility. They want a diagnosis because they desperate for something, anything to help their child.