It may have do with experience. When you have limited experience, you tend to use all your faculties and guided by logical reasoning. When you have lot of exper

It may have do with experience. When you have limited experience, you tend to use all your faculties and guided by logical reasoning. When you have lot of experience, you are guided by past experiences and likely to miss something new, when symptoms are similar to something you have encountered before. Interestingly both my major medical issues were diagnosed by my primar care physician and not by the specialists that I was already working with. Even in my professional work experience, the new problems that may fall across multiple domains tend to be identified/solved by generalists rather than specialist.