I think it's viral redirection of human territorial instincts. Can't let the other tribe seem like they're gaining ground or encroaching on yours. This is one of the most emotionally powerful behavior drivers in apes. Chimpanzees are driven to guard their territory relentlessly when another tribe invades, thats how people draw such infinite energy for political raging. We try to govern our behavior with logic for the good of society but it's hard to compete with instinctive programmed emotions.