If I were to argue my point deeper, I'd say that these societies (orgs) that embrace diversity both are very recent or very recently exerted a significant effort to be more tolerant due to very pressing issues. Otherwise our monkey brains are wired to think "other/them = bad, same/us = good". Groups amplify monkey brain, because monkey brain gets us in groups so that leopards don't kill us at night. Hence the inherence and need for significant effory to override instinct.