IBM's Watson at MD Anderson Cancer center did not work out real well for them. In other words, using AI in the realm of medical diagnostics is very difficult.
Overall, of course, you're right. Liability is the problem with my suggestion. Doctors prescribe to treat, they also prescribe to meet the legally mandated standard of care and minimize second-guessing later. Looking at each patient as a unique snowflake-- or at least, part of a thinner-sliced group-- helps with the first, but directly undercuts the second goal. Such an approach would probably need to originate outside the U.S.
Extracting data from the EMR is very difficult because all EMR was originally intended to only be a storage place for data - not designed to output data back to a user.
Say a user decides to self-diagnose and damages themselves (either through inaction or self-medication or whatever). What difference does it make whether they diagnosed themselves by browsing symptoms on wikipedia or using an advanced diagnosis AI on their phone?