[jbob2000]

Yes. This. My company makes a point to hire out-of-field engineers. I'm a self-taught developer with a philosophy degree. My coworker has a degree in astrophysics. We have a linguist, a theater major, some people with diplomas, and a "dropout". Shooting for Diversity with a capital D is misguided.

[MBCook]

At one point the author talks about the issue that the majority of Twitter hires come from just a handful of schools.

I assume he (or she, don't remember the name) is looking for any kind of diversity, although their experience (and the chart posted) clearly talk about ethnic diversity, which may be what they have the most direct experience with.