How does it work out with a Pitbull and a Golden Haired Retriever?
A boy vs a girl?
Difference exists.
Different things are not interchangeable.
Each set of different things on earth needs its own space.
If different things are forced into shared space, there will be winners and losers.
If competition within that space is restrained (i.e. other than all out war), there will still be winners and losers, but not necessarily the same ones if competition was unrestricted.
If things like freedom, self-determination, self-rule and biological sustainability matter, then so too does keeping spaces minimally multicultural & diverse.