Ultimately it's the platform's choice where to draw the line and it should be a function of their ethos and the observed value to users. It seems pretty clear that Twitter functioned extremely well with a robust moderation team of highly professional experts with clear guidance. Switching to a "free speech" model + community notes has resulted in the platform losing it's appeal. Conversely, BlueSky's model has been rapidly attracting users with their moderation policy. So, active moderation is better than none. QED.
Idk if it's because HN is populated with engineers who can't wrap their head around a non-deterministic solution, but a team of humans with a set of goals are capable of dealing with a problem that doesn't have a concretely defined algorithm.