What you're describing is a durable social system. Social systems are what humans evolved to survive. We're squishy, relatively weak, hairless apes that walk around on the ground. Alone, we're easy prey. Together, you get... well... gestures widely.

If you invest the time and energy into creating a social system, it's perfectly rational to keep it going as long as possible. Otherwise you expose yourself to more and more risk as you go through the world, and must expend more time and energy finding another one, if that's even possible. Before humans built larger societies, that could mean death.