How many people are going to still post death threats, character assassinations, or make racist or sexist comments.

Plenty! People like that aren’t ashamed. They’re proud to be in the group of people who actually count as human in their worldview.

is that something we would want?

The only effect would be to stifle everyone else. If everything you say online is tied to your real identity, many people would have to be the most bland, professional, worksona version of themselves to protect (a) their ability to earn income, and (b) their safety. People talking about their experiences with abortion would put themselves at risk of harassment, eviction, prosecution, and violence. Someone seeking support as they discern their gender identity is now outed to family, employers, people with social and/or economic power over them. When anyone from a marginalized group dares to post, it’ll be just like speaking in real life: if someone’s facts and tone are less than perfection, they (and the entire group which they’re assumed to represent) will be dismissed as intellectually inferior or too emotional.

Fisticuffs? Blade weapons? ….oh. Face to face meetings. (Insert scene from Office Space where that nerdy-looking guy is driving in rush hour traffic playing “Damn It Feels Good To Be A Gangster” like it’s his anthem)