If we didn't, we never would have formed communities to begin with.

I find that hard to believe. The earliest communities likely didn't emerge because a bunch of random strangers got together and said "I feel your pain, let's share each other's burdens."

More likely, parents become grandparents and then great-grandparents, and then with each successive generation the number of cousins grows. These likely had a natural tendency to cohere into clans and tribes.

Maybe then some diplomatic relations with other clans and tribes helped communities grow, but I find it highly improbable that the earliest ones emerged from anything other than organically as families expanded.