It is far simpler than that. De Touqueville (mangled that spelling, didn't I?), in his Ancien Regime history of the French Revolution, very early in, discusses the religious nature of Virtue Signalling and how it differs from a Sin based religion.
Once you make Virtue (rather than Sin) the centerpiece of your morality, you are trapped in a death spiral. Unlike Sin, which is a sort of binary state, Virtue is open ended, you can ALWAYS be more virtuous, and if that is how 'goodness' is measured, you must always strive to be better, to demonstrate how much better you are, and someone is always doing the same thing, forcing you to ever increase the virtue you signal to keep up.
Anyone who attempts to opt out of the system is wicked (Because They are not Virtuous) and must be purged to prove one's own virtue, as the good cannot permit the wicked to go unpunished... and because of course the extremity of the punishment is also a means of proving virtue, you very quickly get to murdering (or in the internet, banning people) for increasingly trivial acts.
At the core its basic human nature and a poor choice of moral judgement. I wouldn't be surprised to learn that hundreds of ancient soceties had fallen into teh same self destructive trap, and we simply never learned of them because they could never thrive... mostly because I also am increasingly certain of the aphorism that there is nothing truly new under the sun when it comes to human activity.