Dividing the discourse into Correct people and The Others Who Shall Be Shunned is exactly the kind of binary thinking that is killing rational discourse.
You are never going to change someone's mind by shouting at them.
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.
The rule is fairly simple, and does not require a list; if you believe that someone should have a different set of rules and expectations just because of a characteristic outside or their control, that is not acceptable.