TLDR: Because you can't act on that data without acting in a racist way that makes the world a worse place. There is no way to use that data without really bad behavior.

Let's break down why it is such an atrocious idea.

Say you have a black man in a high ranking position in your company. Oh, but you want to sieze every advantage possible, and you have data suggesting that black people get lower reply rates on emails. And women get higher reply rates on emails. How do you deal with this situation?

Should he have someone else in the company send high-priority emails for him? Or maybe just set up a dummy email for him with a female hispanic name, and pretend it is his "secretary"? Or maybe he shouldn't be in the kind of position in the first place -- maybe he should be in a more internally focused position? Maybe next time you hire, you should be on the lookout for a hispanic woman for an externally focused position, to make things easier.

There are a huge number of problems with these kinds of actions, starting with the fact that you SHOULD NOT be "dealing with" the situation that you have an employee of a certain race or gender.

1. Flat out discriminatory -- forcing someone to jump through hoops because of skin color / gender.

2.a Fundamentally strikes at human dignity by treating everyone you email as racist, genderist animals.

2.b Fundamentally strikes at human dignity by telling your employees to pretend to be someone "more palatable". Or by having someone do a task, lets say, because the individual is in possession of a female hispanic name. Everyone is dehumanized.

3. Liable to twist thinking. After reading that article, and next time you're hiring someone, you brain has a good chance of (inadvertantly) jumping to the notion of how the applicant's race / gender is going to impact email reply rates. We've agreed as a society, for good and just reasons, that hiring decisions and compensation decisions should be completely blind to those (and other) factors.

4. Any actions taken to hide or shield people who seem to be less acceptable or attractive to society simple reinforces their position. The idea that there aren't successful [insert race / gender] people in [profession] is reinforced by hiding those who are.