Rationality is a methodology, not a position, and name-calling goes against it's core principles.

To quote Vlad M:

In many ideologically charged topics that are a matter of culture wars and political battles, a key strategy is to create an association in the public mind between one's favored position and a vague and general feeling of righteousness and moral rectitude -- so that in the future, ideological opponents can be defeated by attacking their moral character, regardless of the quality and accuracy of their arguments and position