Eg, I too would love to have the discussions you speak of. Despite this, I often see an escalation in tone and fight the urge to respond in kind. I often fail at not responding in kind. Doing so of course escalates the conversation, something I've now contributed to, and it will likely escalate yet again. Over and over, until all reasonability in the conversation is dead.
If I knew it wasn't allowed, and especially if it gave me some type of non-public meter of how much further I can go before my conversation will be blacklisted/etc, then people like me have clear visual feedback over .. well, not being such a douche.
It would be like having a state patrol a few lanes over on the interstate. If one is around, most people behave quite well, because we can all see what will happen if we step out of line. Likewise, our speedometer gives us the visual feedback to know what is out of line (with regards to speeding of course).
It would feel very weird at first, especially if the system was not perfect, but at it's root I think it's needed for us to be able to discuss sensitive topics. Which, tend to be the ones we need to discuss the most.