It should be noted that healthcare.gov might be the highest traffic website launch in the history of the internet. With millions of visitors on day one, I certainly can't think of one that would even compare.
They are dealing with scaling issues that are almost completely unprecedented. Every other e-commerce site that deals with many millions of visitors a day has had months, if not years, to figure out the touchy parts of their infrastructure and make adjustments while the traffic ramps up.
Given this, I can't help but think that 90% of the scorn heaped upon healthcare.gov is politically motivated. When Twitter spent YEARS going down on a regular basis, or Simcity just completely shut down on launch day (with a fraction of the users of Obamacare), nobody demanded the companies that running them be shut down. Shit happens when you build a website that gets incredible amounts of traffic. It will work out just fine.