Back in the 90s, I was a research assistant to a couple of doctors who were working on that kind expert system. The main difficulty is the lack of electronic pa

Back in the 90s, I was a research assistant to a couple of doctors who were working on that kind expert system. The main difficulty is the lack of electronic patient records. Most things in medicine are still done on paper. The other problem is that an expert system that does patient diagnoses is regulated by the FDA as a medical device, and it's incredibly involved to prove that it works well enough to be safe. That's why you see these systems pop up in research settings all the time, but very rarely deployed in the real world.