Scalability problems plague the creation of large web sites. This is especially poignant, given the Healthcare.gov web site fiasco:
Large systems, too complex for individual comprehension, must be subdivided into smaller tasks coordinated between groups. In fact, a large portion of software engineering is devoted to the documentation, notification, and management review needed to coordinate large projects.
Thus, it is not uncommon for large IT projects like this to have overrun costs or fail:
One study shows that 34 percent of projects are unqualified successes, 15 percent are complete failures which were abandoned before completion, and the remaining 51 percent, like healthcare.gov, fall somewhere in between.