This seems pretty dead-on. When hiring for a company, it's generally understood that having talented developers in your company will help attract other talented

This seems pretty dead-on. When hiring for a company, it's generally understood that having talented developers in your company will help attract other talented developers. As the groups mentioned in the above comment have shown a stronger presence, even more people from these groups appear. And, as the number of developers has dwindled, there has been less reason for others in their profession to come and share.