.. if they had some sort of staggered entry to the website. A very simple rule such as only those born before 1950 can register in the first week, those born before 1960 in the second week and so on. This would have alleviated a lot of the traffic issues and given the developers some breathing room to fix bugs and scale their solution.
Controlling traffic, while you scale your solution, is not a novel concept. Gmail did this through an invitation system when it first started. Facebook only allowed certain universities at first etc...
Its strange but this reminds me of why, they say, we have mirrors in elevators. Folklore suggests that in the early days of high rises, people tended to have an unrealistic expectation of elevator speeds, probably, because they had nothing to do in the elevator. Adding mirrors in the elevators gave people something to do and took the pressure off the elevator engineers.
If people expected a government run web site to scale perfectly for millions of users within the first month of its deployment, those are very unrealistic expectations.