Here's what the article has to say, and I agree with it:
Why diversity is important to Hacker School
There are many reasons why diversity is valuable, but there are two reasons why it is especially important to Hacker School as an organization.
The first is that diversity helps to reduces the harmful effects of stereotype threat. Put another way, we focus on diversity so Hacker Schoolers don’t have to. We want you to be able to focus on becoming a better programmer, not being the only person like you in the room. The more diverse Hacker School is, the easier it is for a greater range of people to do that.
Second, a large part of the value of Hacker School is what Hacker Schoolers learn from each other. Hacker School relies on a diverse range of experiences and perspectives; if everyone were the same, no one would have anything to learn from each other! Our self-directed and peer-driven educational model is in this way very different from traditional, one-size-fits-all approaches to education.[1]
Given this, it’s unsurprising that Hacker School has gotten better as our community has grown to include more women, trans people, genderqueer people, older people, younger people, parents, and people from a greater range of racial, ethnic, and socioeconomic backgrounds.
[1] Consider a traditional lecture-based class with a fixed curriculum. That model is built around homogenity, not diversity: It’s much easier to operate if everyone involved has the same background, interests, learning-style, and rate of growth. Our model is the opposite: It’s helped not harmed by diversity.