I think it's more about setting standards of conduct. The ones that don't adhere to it reveal themselves to be outsiders or brigands, the ones inside it start off with a baseline that offers mutual cooperation and a basic means of communication. It's a filtering mechanism with a bonus feature. That would lend more resilience within a culture which would help it survive. Most that didn't probably did die off or never survived to be large enough to be considered a culture.
I think it's more about setting standards of conduct. The ones that don't adhere to it reveal themselves to be outsiders or brigands, the ones inside it start off with a baseline that offers mutual cooperation and a basic means of communication. It's a filtering mechanism with a bonus feature. That would lend more resilience within a culture which would help it survive. Most that didn't probably did die off or never survived to be large enough to be considered a culture.