Back when the internet was still a fairly new thing, in the early '90s, I figured out that the reason we get all riled up in front of the computer is that we don't have an outlet for our emotional energy. Our anger or whatever just stays bottled up. Face to face, we can at least talk and let some of the energy out verbally.
The main point of my comment was, however, to consider how, in both cases, the idea is to manipulate someone's feelings, by invoking them on subjects they have strong feelings and opinions about. I read a lovely article about propaganda which goes into detail about how we are manipulated in this way in day-to-day life. I will post it later on in a separate blog entry.