[Chris2048]

It doesn't seems to me that racist "clearly and unambiguously identifies those people", especially as stated "no group or party has ever applied to itself".

In contrast, there are groups that have applied to itself the word "communist", and so far as it applies to them, it is clear and (somewhat) unambiguous. The scope, however, of who it doesn't apply to, and who it may be used against is ambiguous e.g. McCarthyism.

This doesn't mean that I agree that the word is purely abusive (and as such agree with MM), but I don't think his opinion is either completely wrong, without merit, or obviously so.