I deny the premise of the OP's doctor analogy. Given a rare liver disease, and the amount of information available on the internet, and access to doctors to ask questions to, a motivated learner could become quite proficient in understanding how the liver works and how it is affected by a specific disease. The patient does not have to become a doctor to do this. A doctor has to learn many, many things to become a doctor. Whereas the liver disease sufferer only has to learn about one thing. It is easily possible for a lay person to learn enough about their condition to have a meaningful "technical" conversation about it with their doctor.
That would only work if the learner is so motivated that they spend months poring over medical and biology textbooks to understand enough background, and then learn how to read scientific papers and interpret studies for statistical significance, to get up to date on the latest research. And of course they also must have the aptitude to do all that, to get to the point where they can start meaningfully questioning the doctor's recommended course of action.
Otherwise, they're still just going to have to trust the doctor.
