Moderators can help reduce the impact of trolls and grifters and provocateurs, but not if they are outnumbered and overwhelmed. This is why sites like Twitter and Reddit etc are always plagued by these problems despite having moderation teams: a site's user base can only get so big before the toxicity reproduces exponentially, radicalizing some into extremism and baiting anti-extremists into argumentative styles they otherwise would not have adopted. The social media site becomes the site of an actual culture war.