That is true, however even your internist is interested in your "primary complaint". There is this idea that one problem should be addressed at a time.
Not so much for anything serious or unusual, in my experience. If you have multiple complaints, the first thing doctors look for (in my experience) is something tying them all together. If you only have one complaint, they often ask if you're having other symptoms that you've just overlooked. I found out that a number of... corner cases that my body has just always had, were not normal, because of this. (There was fortunately nothing serious).
Of course, for very common symptoms (like headache and nausea), they usually just treat the symptom.
Of course, for very common symptoms (like headache and nausea), they usually just treat the symptom.