At least part of it is that no one has come up with a document format that suits everyone. Doctors want to scribble notes with a stylus but when you digitize that you don't really gain anything, other systems don't know how to interpret those scribbles. Suggesting doctors enter fields into a form instead of scribbling notes will get you no where, doctors are the stupidest and most stubborn smart people you will come across. Not that this is perfect anyway, sometimes you really do just need those random notes that don't really fit anywhere else. Some of the younger ones will type instead of scribble, but it's still mostly free form text and not data. The industry is still stuck on the idea that one doctor visit == one patient record as well, the thought that doctors could input blood pressure readings in their own section and have it display the history as a spreadsheet (or even a graph) has not gained any acceptance.

So it's not just about how we transfer information but how it's created as well, we haven't invented the right set of primitives to store it in the first place. I've spent a bit of time thinking about how I'd improve things and think things need to be more like emacs org mode or a jupyter notebook than any current EMRS, but even that might have to wait for a generation of scribblers to die.