Anyone who has researched medical symptoms online comes away slightly terrified with dozens of contradictory sources resulting in a very confident self-diagnosis of something terrible. Blurry vision? It might be diabetes, cancer, rickets, or myopia. Or all of them.
Even if your diagnosis isn’t at all correct (It’s not—you just have dry eyes today), the research and diagnosis process gives you a sense of why it’s a difficult task. The availability of lots of information, wide variation between patients, the difficulty of getting time-consuming medical tests, and potentially high stakes all contribute to making medical diagnosis a difficult thing to do.