Diversity always happens when any number of peopel combine forces and effort. 10 people on balance will come up with more different ideas than 1 person. 10 people can do more than 1 person, usually.
But not always. 1 person can come up with more better ideas than 10 people. While 10 people can do more than 1 person, sometimes 1 person can accomplish much more than 10 people.
There are just too many variables. To say diversity is in itself a great strength oversimplifies things.
There is diversity of race and gender, and then there is diversity of cultural values. The first kind of diversity can be a good thing, but the second kind will never work.
We see many who refuse to speak English even if they can.
They take over small towns and / or communities with no intention to blend in. Some places are having turf wars between different Mexican drug gangs.