They would be prevented from criticizing or harshly characterizing members of their own group or other victim groups. Hate speech laws also must depend on an accurate representation of how speech works, reasonably predicting how speech will be received. If not, application of the law becomes arbitrary and capricious. The ironic beauty of speech is that neither the speaker nor the text can control the reaction of the audience, which may vary dramatically from one hearer to another. It is safe to say that the interpretations of a particular word or string of words in a particular context amount to some multiple of the total number of individuals and groups receiving it.
Language is simply too mercurial for the constraints of legal definitions.
Hate speech uncovers the haters. It exposes the ignorance, fear, and incoherence in their views. It warns, prepares, and galvanizes the targets. It provides the police with suspects and the prosecutors with evidence in the event of a crime. It enlivens the bystanders.