Rav Kook on the end of hatred

All matters of hatred, and all of the letters of the law
which apply to them, these were only stated in cases where we already knew that
the precept of reproof had been administered to someone. And since we don’t
have in this generation, nor have we had for several previous generations, as
Rabbi Akiva testifies, someone who knows how to deliver reproof, therefore,
they are not longer applicable, all of the laws referring to ill feelings and
the hatred of brothers have become like the case of the rebellious son, a
banished city, and a contaminated house, according to the one who says there
were never such case, and never be in the future…”

Letters of HaRav Avraham Yitzhak HaCoheen Kook Part 1, 305 (Torat Eretz Yisrael pg 82)