[petercooper]

Pro-diversity, ex-conference (not this one) organizer here.

I can't speak for what GitHub did or didn't do, but a common problem is that there is a huge step before review that you can't skip. You must coach, encourage, and counsel the types of people you want to submit talks! If you don't, don't be surprised if they don't submit because of the treatment or impression they have from other events in the past.

Pro-active outreach to underrepresented groups is the way to get better events and a blind review process is no panacea despite many organizers seeming to think it is.

It's suggested here that they did blind review and then wanted to tweak for diversity. That's just not how it works. You need the diversity up front in the submissions.