There are always a limited number of possible discussions that can happen at a time. Those with "outlandish" views, namely those who believe some people's live

There are always a limited number of possible discussions that can happen at a time. Those with "outlandish" views, namely those who believe some people's lives are fundamentally worth less than others often turn this into a strategy. As long as Holocaust deniers are tolerated and especially counter-argued by everyone, Holocaust denial will be all that is being talked about because they take the stage. Even if they lose the discussion, they win the topic of the day. And that topic gets gradually normalized into an acceptable position, pushing away others silently.