Because having a diverse employee pool has advantages as it helps avoid group think, reduces mental blind spots, and introduces new perspectives. Diversity is itself good for teams.
What does ethnic diversity have to do with intellectual diversity? Do blind testing.
Because we live in a society and ethnicity has massive effect on culture. At the same time, blind testing only tests what is on a test. If the test makers aren’t diverse then the test won’t test diversity. Ethnicity is an incredibly easy proxy to use.
I grew up in a rural area. The difference between me (white) and one of the two black kids or two Asian kids in my grade in terms of “perspective” or “group think” would be far less than me and a white kid from even the nearest big city.
Also, how the hell does “perspective” matter for say…an accountant? Programmer? Vet tech? I’d buy it in marketing, product development, and some other random situations, but as a whole?