What Daryl Davis does might work if you are talking about a very small group, but by the time it reaches percentage points of the population that method no longer works as the societal support structure grows from these vial ideologies, the weaker an approach based on societal influence. Eventually the only option left is violence as you have two opposing societies and can no longer pull "radicals" out of their hatred.
Just like with the Fascists of the early 20th century, the only option left was to expunge these hateful societies.
Oh ya, the right famously doesn't point fingers at every point in time, while calling to kill left leaning people.