This is coming from someone who is under 2 months away from having her PhD: having a PhD does not mean you know anything about reality-land.

The truth about a PhD is that it's extremely specialized. She may have very little or only very basic exposure to information about the particular issue she was spouting about. Her expertise may be in some other area, in which she's probably very, very good and very knowledgeable - but probably not this one, or as others have said, she'd know that it's a spectrum, that there are multiple treatment options, etc.