This "melting pot" simile just doesn't work anymore - if it ever did.

Big cities where our ancestors moved had neighborhoods for those of the same background. You had Little Italy, Chinatown, etc and those places had a mixture of the customs of whatever culture and festivals. Not all spoke English.

Think of today's big cities as a "stew" rather than a big, bland "soup" where everything is cooked together to an overcooked, flavorless mess. The "stew" has chunks of ethnicity that retain separate flavors and brings the finished dish to a delicious and flavorful meal.