[Spooky23]

Legacy isn't a dirty word.

But the fact is that these ancient systems are nightmarish to work with, and because they are so ancient, they predate many of the standards and capabilities that modern systems have.

I spent a decade working around a big legacy system originally built on a Sperry mainframe in the mid 70s. The system was awesome in some ways -- amazingly performant, efficient and well tuned. But the reason it was so awesome was it's downside as well... it is almost static, changes are difficult/impossible to make. In the EMR space, things have to change, but because it uses an ancient/domain specific set of artifacts, you're stuck with a small number of incumbent vendors with whatever functionality they are willing to do.