Why Do Debates Get Reduced to Name-Calling?

First it was Rush Limbaugh and his "femi-nazis," and now I see Stuart Taylor Jr. refers to "feminist careerists" in an Atlantic Monthly article. Without even trying to figure out just what those terms mean, I am reminded of what I used to tell my children when they were young. Anyone who must reduce an argument to name-calling and labeling is both language and idea bankrupt. I guess some people never grow out of it.