I'm sorry, I'm just gonna reply to this random comment so I can add my two cents to this thread. (I totally agree about the comparison to mechanics performing on a running engine though)

Why does the world need to boil everything down to simple generalizations and stereotypes? Of course you can find doctors, engineers or lawyers that are lacking in knowledge of other areas in life (nobody can have an in depth knowledge of everything). There are also enormous disparities even among these careers with, for example, someone being a public defender compared to a high profile prosecutor.

By this logic, all mechanics, farmers, etc. are also highly dysfunctional "outside of their expertise" if we're basing this all on the fallacy of anecdotal evidence. I can come up with examples of people with zero common sense that work in any variety of fields, but I don't because I understand that reality is much more nuanced than people pretend it is. This oversimplification of entire segments of the population is what leads to all kinds of animosity and prejudice in society and it needs to stop. The world is a big place with billions of individual life stories and we would be better off if people acted that way.