> please specify which kind of diversity fosters innovation

To keep an open mind I did a thought experiment and found a few: entertainment, fusion food, music, those things I'd imagine benefit greatly from diversity.

True, but still better than the alternative.

Often it seems tech companies (and certainly many others) almost explicitly hire people with similar viewpoints--not merely accidentally arriving at homogeneity by way of socioeconomic strata, but by strongly broadcasting ideological statements.

Maybe they should do something geographical. Let's say hire a person per country and then start again. You know building actually distributed and diverse teams.