Back when I played dark age of camelot we called this "BAF" or the "bring a friend" mechanic. Almost any mob you pulled if it ran by another mob would bring it with them. Now granted almost all dungeons in that game were out in the open world so it was a bit different. But it made pulling strategic. It also made it make more sense. But yes I do think it's funny sometimes to see two mobs talking, I pull one and his buddy just sits there like "ya bob I know.. bob...hey where'd bob go? eh fk it".