It's really simple: to pull off a major coordinated attack like the one described in the opening paragraph of that piece, you'd need dozens if not hundreds of hackers all working in concert and all achieveing their goals at the same time on the same day. This would be a serious threat if hackers were coordinated, social people who could be organized to do such a thing. But as the article admits, hackers are loners, and those who actually have hacked sites and/or caused disruption or damage acted alone. Also, organized hacking would be a great potential danger if hacking were a teachable skill, which it is not.