They and the people for whom they vote have thrown those slurs around so much that the slurs no longer carry weight with people interested in rational discussion. Plus, I think most people with much sense intuitively understand that the person shouting slurs in a debate and resorting to fallacies is behaving like that because they're losing and the facts aren't on their side.
When is the last time I responded to the three I think you have in mind? Months ago. Who needs who? I spoke of some here being mentally unwell and rather pathetic and desperate. I think this tack has illustrated the truth of those characterizations quite well.