I understand it's chic to think that Healtcare.gov is "just another website", especially among a certain crowd who think that all development is web development, and best done on a MacbookPro using RoR/node/<functional language Y>/Go + <insert fad-of-the-day JS framework here>. It's a mistaken impression, though, because we aren't talking about some from-scratch system. We're talking about communication with and between a lot of legacy systems requiring what is almost certainly a frankenstein-like nightmare of patchwork APIs that dive into programming languages and styles hipster 20-somethings at hot S.F. Start Up X wouldn't understand because it's beneath them (I'm exaggerating and generalizing here for effect--this isn't to impugn all 20-somethings, start-ups, etc.).
Honestly I don't think there is any contractor who could have pulled this project off flawlessly, or even very much better than the group of misfits who did Healthcare.gov did, just because of the sheer complexity of the project compounded with the increased politically-motivated interference from government officials that comes with such high-profile projects.