Everyone has a gun? Rational people are theoretically less likely to try and piss people off, because they know everyone is carrying.

It's super-easy to sue people for hate speech? Rational people are theoretically much more likely to consider their words, because they know everyone can get their ass fined and possibly imprisoned.

(The obvious problems are of course that not everyone is a perfect rational being with no emotions or extenuating circumstances, and that there are people who will immediately start trying to game any system for profit - goading someone into doing something that gives you an excuse to punish them for Bad Behavior, whether via the gun in your pocket or the State's justice, is an old, old tactic.)