It kills far more than rational discourse. People have had their careers and lives ruined over what somebody else deems to be wrongthink.
Are you suggesting that there are NO viewpoints that are worth rejecting out of hand? If someone thinks that all black people should be killed, we need to entertain his views?
There are limits, and some views are not just a difference of opinion. Some viewpoints need to be shunned.
You are never going to change someone's mind by shouting at them.