When you're actually talking over someone, it's as if you're just pontificating and they're not even there. And their body language - they're trying to get away from you. And if you're pontificating at an audience, and there's a break, the non-martyrs in the audience are not going to come back. I mean, they just want to get away from you.
Have you ever heard someone tell a story but felt they are just mouthing the words without being emotionally connected? When you do this, you often create a more negative reaction than if you hadn't told a story at all. That's because others can see that you're just going through the motions.