I was recently in a situaton where a company created a mixed team of women from an equatorial African country and a S.E. asian country (over my strong objections). The Asians spoke little English but were very skilled and were hard workers. The Africans spoke excellent English but were less skilled and-worse-required anyone giving them tasks to couch the instructions in delicate, even felicitous language, and did not accept correction no matter how it was offered. When we put some of the Asians into leadership positions, a situation was created that nearly devolved into physical violence. The Africans ignored any instruction that they felt was given "disrespectfully," and the Asian team leaders became more and more frustrated. We had a few near-fights and daily drama that greatly interfered with a delivery. Upper managment eventually intervened and split everybody up again. It was an epic fail.
You are obviously mistaken. In my corporation, I am told over and over and over and over and over and over again that diversity is our strength. Just look at that tower of Babel. Oh, wait.