Refusing to self censor is a failure. Specifically a failure to communicate because if you dont self censor no one is going to listen or be influenced by your opinion.
People who launch personal attacks are not censoring anyone. They are just launching personal attacks and yes ending conversation. If you want to debate then you have to follow the rules. If you want to keep talking you are free to do so hence you are not being censored. Its just that no one is listening to you.
It is not Common Sense to expect people to Self Censor.
I don't expect anyone else to Self Censor in order to talk to me.
Yes, people who shut down debates by launching personal attacks are censoring because they are preventing public speech they do not like.
There are no rules requiring Self Censorship. That is not a reasonable expectation.
It is telling that you want for "productive discussion" to involve those you disagree with to have to self Censor, and for youto be the Judge of when they fail to do so well enough.