One first needs to appreciate the many attempts failing at it. Reddit, Twitter, social media... They all were bad to begin with, but deliberately made worse still, to the point of not fulfilling their
raison d'être anymore.
You need a functional format for group discussions (existed, killed off). You need functional standards for civil discussion (exist, see science, people somehow forgot). And you need to realize, anonymity is anathema to having a civil sphere (You don't need to give your real name, but for social self-regulation to work, an identity is necessary).
AI quite possibly could help a great deal with this. Sensible automated (and consistently reasoned/reviewable) moderation of internet forums is wildly underexplored.