This is because a random person you interact with is more likely to be close to the mean belief on that dimension.
As you interact, you both pull each other closer to the midpoint of your beliefs.
When this happens enough times, everyone is pulled to the midpoint of the distribution of the population.
Often, this mid-point is the ground truth… because the asymmetry of belief is tuned towards the thing that people can verify with their own two eyes.
But sometimes there's an asymmetry of belief that allows a compounding collective psychosis to take hold.
Imagine if everyone on earth used only the same model for their chatbot.
Any bias in that model's perspective could lead to shared psychosis.