This statement basically could not be less accurate. The NFL itself thought there was a huge problem with the lack of black coaches in the NFL, so it took a pro-active approach by making the Rooney Rule (http://en.wikipedia.org/wiki/Rooney_Rule), in which a minority head coach must be interviewed (not hired), in the case of a head coaching vacancy. And what happened? Well the number of minority coaches role greatly from 2 at the end of the 2002 season to 7 currently.

Basically the NFL front office realized that a lot of the owners had some unconscious bias against minority head coaches, and thus they made a rule which forced them to at least acknowledge there were quality minority coaching candidates out there. And once the owners were forced to confront this, they started to agree and hire minority candidates.

I think there are a lot of parallels between this and the current gender disparity in YC. In order to solve such a systemic problem, you have to take big steps. YC doesn't want to take big steps, and thus the problem wont get solved, and people will continue to muse about how women just aren't trying hard enough. Reminds me of the prevailing wisdom in 2000 when everybody said minority head coaches just didn't have what it took to run an NFL team.