I think that it is just as important to talk about the extremes and the bad ideas as it is to talk about the good ones. We bring up the extremes because they're

I think that it is just as important to talk about the extremes and the bad ideas as it is to talk about the good ones. We bring up the extremes because they're there, and they can be tempting, and so we should warn each other about them. Saying what you're saying usually (but not always) is an attempt to not address the usually perfectly reasonable point one is responding to without outright defending the extremes. Extreme ideas do need to be pointed out precisely to do what you want: prevent the reasonable discussion from becoming one between two extremes.