This because the doctors insisted on using a DOS based patient journal, as they could operate it completely by keyboard while maintaining a conversation with the patient.

I speculate that one reason for this is that DOS allowed each program to have full keyboard access, while Windows and other GUI has to reserve certain keys for managing the UI (switching between windows etc).

Thus what was earlier a series of single key presses now involves holding down a modifier for the duration. And that is if the developer even remembered to put in a hotkey for said action.