You're right, but don't forget about all the many hypochondriacs out there; unfortunately, given the current Western model of medical care, a doctor may not know their patient well enough to know if the patient has rationally, logically, and objectively diagnosed themselves, or if the patient has a psychological disorder instead that's manifesting as a rare physical disease.
Yes, the situation today is an extraordinary dilemma. I'm not sure why hypochondriacs are so common today but I would speculate that this it is because many people are starved for attention.
But you have a situation where a doctor, who is a highly professional but not a research scientist, confronts a growing number of individuals who have gotten a mass of scientific information from the Internet but are proportionately even less likely to engage in a rational process of determining what malady they have. Some of these patients probably know what's wrong with them much better than the doctor but what percentage is it? What is likely to happen given a health care system which measures the doctor's visit times by the second?
Perhaps there should be online exam for patients wanting to diagnose themselves, including basic test of inferential reasoning? Hey, there's a startup idea for you - a website which prepares your diagnosis using language your doctor can understand.
There's also something called "medical students' disease" (http://en.wikipedia.org/wiki/Medical_students_disease) where people who research medical conditions become convinced that they have those conditions. It's easy to see how a hypochondriac researching their medical problems online would end up developing medical students' disease.
