Blinding an interviewer by changing pitch/modulating the voice does little to erase the actual disadvantage. Few are arguing "people that sound like women are discriminated against", they're saying that the systems are set up in such a way that there is a bias against women that encompasses the evaluation of their experience, their work profiles, the topics they're interested in, the projects they've completed previously, etc. It's a systemic disadvantage, and that experiment isn't getting at the issue being claimed.

As just one example, women still do the majority of child rearing, especially babies. People who want children make that choice, but men typically take a few weeks out of their career whereas women take months or more. That's a systemic disadvantage women suffer.