Something people don't always appreciate is that relationships don't scale linearly. In a family of 5 there are 10 possible relationships. In a group of 50 there are 1,225. And there are 124,750 possible relationships within a group of 500. One reasonable explanation of Dunbar's number is that group cohesion requires people to comprehend not only our relationships with other individuals, but also some understanding of how two random people we know interact with each other. Otherwise we risk inadvertently stirring up disagreements between others.
This is a companion discussion topic for the original entry at https://jlericson.com/2020/09/24/ignoring_others.html