Part of it is that she's just parroting the establishment media's line. That's what she always does. The last time Katie Couric had an original thought, if she ever has, is a mystery to me and probably everyone else.
Part of it too, I think, is that she is genuinely not very intelligent. It would take some nerve to sit there and rail against "fake news" when you got caught misleadingly editing your gun control special to make pro-Second Amendment people look stumped at a question, when in fact that is not what happened at all.
Unless it's not a matter of nerve at all, but it's really a case of your not having the brains to know the difference: