In my opinion none of them were capable of designing a user facing application. It was also built as a client/server desktop application. Not really a good choice in my opinion. Sure there were no offline PWA at the time, but by contrast if your SAP backend dies all the local applications in a hospital e.g. writing the release report also dies.
Needless to say given it's immense complexity it was also impossible to use this monstrosity elsewhere.
But replacing it with Cerner in a $16bn project is just sad.
It was a truly open source project within the VA with programmers customizing this national patient record software in cooperation with doctors (to meet their needs) locally and sharing the modifications nationally. Perhaps its greatest technical challenge (besides complexity arising from decades of evolution) was finding programmers to work with the MUMPS language that it was written in. FYI MUMPS is a language with an integral db -a concept which was out of vogue for some time.
Political challenges are another story[4].
[1] https://sourceforge.net/projects/worldvista/ [2] https://www.hardhats.org/history/hardhats.html [3] https://worldvista.org/AboutVistA [4] https://www.politico.com/agenda/story/2017/03/vista-computer...
Why Cerner? I don't know.
However, despite being a critical, successful piece of open source software that had massive investment over decades, it's being abandoned for a commercial system, Cerner, in a $16bn project.
https://ehrintelligence.com/news/va-cerner-implementation-co...