Every person in the history of the world has a million unspoken, unidentified assumptions based on where and how they were born and raised. Our (early) experiences shape us profoundly, and it's impossible to overturn that even if you try.

Nobody is "neutral". It's simply impossible. Therefore, diversity.

I think this supports the statement you are responding too. The million factors impart a diversity of perspective regardless of whether there is diversity of racial heritage. Does focusing on diversity of racial heritage optimize diversity of perspective?

So apps developed in China or Japan or Nigeria will be at a disadvantage because they lack design diversity? Or will thru do just fine if they all went to different schools of design?

what are you trying to say here? that all designers are good at designing for people with different backgrounds? therefor we don't need to keep diversity in mind when hiring them?

I'm saying that valuing somebody for their background instead of their skills is a subtle but very real form of bigotry while also betraying the reality that you can understand/empathize with people from different backgrounds without being part of that background.