I mean it would be a cool feature notwithstanding that I personally have never seen a case where this could have prevented anything. Critical reading skills should prevent people from getting away with misquoting people, and lying about the contents of dms (or denying the existence thereof) would just cause a standoff where one party would look silly after theymos or any moderator? checks their PMs.
Maybe you’re not familiar of my situation with a member Vod? He spent years attacking me with lies and posting false information all because he misread a PM and made assumptions that when he discovered his idiocy he chose to lie and attack instead of admit his mistake. No administrator or moderator was any help in bringing the truth to light and chose to blame the victim and urge forgiveness of the liar. Being able to show that I was posting real quotes and Vod was lying might have saved this community a massive drama that ultimately led to Vod not being able to post here anymore and a lasting suspicion around me for being attacked with lies by a crazy person.
So if critical reading skills could have helped avoid that situation then users with critical reading skills here are in short supply.