"recently only works so much better because..."
because the domain experts of the system now know what it should do. You're only a domain expert by experience, not by taking a class.
When you do stuff complicated by human factors (aka diverse user base, laws, regs and legacy systems) and not physics for the 1st time, it's always bound to fail on some major items. Nothing new here. Facebook had launch issues in the past, same as Google... also remember Apple Maps fail or even the days when good'ole fail-whale was incredibly frequent?
The obamacare site failed because of the deadline imposed indirectly on it... that the law require everyone sign up before Dec. The Republicans just stuck their finger in the wound to make it sound way bigger than the real problem, which Obama knew was a mistake on his part. This failure is not the tech, but the poor clarification of requirements. And guess what? Healthcare systems are piss-poor in use cases and design from the get go.
I seriously doubt Google, Amazon, a bunch of smart ass college whiz kids or the such would have done better within the same man-hours used. Of course college kids could have done better, but would have worked twice, maybe 3x as many hours to get to this point.