All of that sounds pretty cool, especially if your only focus on diversity is limited to the food you eat and the songs you listen to.
But the only real thing that makes it possible for people to live together is uniformity. Same language, same customs, same expectations, at least same calendar.
It seems to be absolutely laughable that people from anglophone countries nowadays love to talk about diversity when they are unable to find a common ground with their rural compatriots and all their “diverse” friends are the same middle class people grown up on Hollywood movies and Rowling books.