The rules of decorum have gone out the window and did so long ago. Conservatives think liberals are wrong and/or stupid. Liberals think conservatives are evil, which is why they see it as immoral to ever compromise with conservatives and readily smear them as bad/stupid/irrational/at-best-uneducated no matter what they say and increasingly physically assault the "haters" for daring to utter their "hateful" views in public.
You can't have respectful rules of debate when the authoritarian left sees it as a moral right to verbally attack and try to destroy the life of anyone who publicly disagrees, even their own members bringing up "hate facts", and engage in property destruction and physical assaults against conservatives because they see it as literally fighting evil.
We won't get decorum and decency back until true liberals (I put Stephen Molynaux, Sargon of Akkad, the late Christopher Hitchens in this category) rein in the authoritarians who see it as their right to control every detail of our lives for an imagined utopian vision with the emotional investment of religion while calling everyone who disagrees with them horrible names at best, assaulting and calling for their arrests and death at worst.