"Hate speech" is a moving target; attitudes towards which speech qualifies as hateful are constantly changing, and never consistent amongst individuals. Allowing any person or group to define what qualifies as hate speech is necessarily going to reflect their biases, and, in the long run, make those hateful ideas more attractive by virtue of creating taboos around them. So hate speech not only is undefinable and largely ideological, but worsens the problem it tries to solve.