Maybe you need to look a little deeper. Is Trump 's campaign built on policy or intelligence? It's built on saying outrageous things. Kelly served up to Trump exactly the kind of question he wanted. Fox tried to throw the debate to Trump. If Kelly wanted to hurt Trump she could have asked him any number of questions that would have tripped him up, but no, she played right into his campaign.
Imagine if she had asked him about Common Core. It could have revealed right then he doesn't even know what Common Core is.