I mean, being qualified is never the only piece of the "getting hired" puzzle, right? You want someone who fits well in your team, is generally interesting, is eager to learn, and possibly fills some other niche that you feel your team is missing. I think it's a fair question to ask, "Will this person provide a unique perspective within our team?"

It seems simply that Etsy is trying to fill a female niche and add female perspective. It's not like they're hiring random ladies off the street, their hires have gone to hacker school and are clearly capable given the opportunity. Software isn't written is silos where you don't talk to other people about what/how/why you are going what you're doing.