The rules of discussion: I respect the other person and I am interested in what that person has to say. That person respects me and is interested in what I have to say. If I did not respect him or was not interested in what he had to say, or vice versa, there would be no point in having a discussion. If I partake in a discussion, I hope to learn from the other person, as well as to teach the other person some of my ideas.
The rules of compromise: I want something. The other person wants something. Unfortunately, for me to get everything I want would deny the other person everything that he wants. If I can accept living in a world in which I do not get this particular thing that I want, I am willing to enter into a compromise.
The rules of debate: I have a belief that I hold very strongly. The other person holds a belief that he holds very strongly. We argue, using evidence and logic, as well as our own intelligence. And hopefully, I am able to prove my point and "win" in the judgement of a third party.
It's rare for a conversation in our political culture to only be a discussion, a compromise, or a debate. It's actually healthy to combine each of these three categories, depending on the situation or the topic at hand.
Donald Trump is not a good compromiser or discusser (apparently, that's a word). He disrespects almost all of his interlocutors. And, by the standards of academia, he's a terrible debater. He doesn't rely on evidence, facts, or logic, and he assumes anyone with a different opinion is stupid.
And that's why he'll win.
The pundit class is naive to think that Hillary Clinton, with all her intelligence, would destroy him in a debate. As far as the general populace is concerned, a good debater doesn't stand a chance against a bad debater. Donald Trump is not a civilized man. And you can't use civilization's tools to defeat him.