Sure it matters. Who doesn't do well due to stress? I think you'll find women, minorities and basically a lot of people outside of the cultural norm/majority do poorly.
That's not an argument that you can eliminate test anxiety, but certainly if we can reduce it without destructively eliminating the high value candidate pool we should do so.
What you are saying is an ethical/moral consideration and it is a valid one. When I said it doesn't matter, I meant that FAANG is commercially not incentivised to account for the anxiety factor. Even if they miss out on good candidates due to their anxiety, they can still choose from plenty of good candidates who don't suffer from anxiety. Given how many people are aspiring to join FAANG, I'd assume it's a buyer's market for these companies.
I'm not sure that's true. What you describe is the case for any individual candidate, but doesn't account for how those candidates interact with one another. Specifically, it has repeatedly been shown that more diverse teams will consistently outperform more homogeneous ones.
If your company only hires above the 95th percentile but their method for finding that quality cutoff is heavily skewed towards a certain demographic, in the long run that company may well perform worse than a company that hires at the 80th percentile but without the demographic skew.
That's not an argument that you can eliminate test anxiety, but certainly if we can reduce it without destructively eliminating the high value candidate pool we should do so.