A doctor has to mostly always treat common cold, and influenza. But that's no excuse for her / him to not know the purpose of the left pulmonary vein. The more basics they know, the better doctors they are.
Sorry if this analogy is a bit extreme, but I want to make a point.
I think a more apt analogy would be if you would disqualify doctors who don't know the nucleotide sequence of the genes that code for the cytochrome p450 enzyme process from treating your cold or flu.
The left pulmonary veins are gross anatomy, akin to knowing what an 'if' statement is. Knowing the current state of the art in determining a minimum complexity for an operation on an obscure tree implementation is deep domain knowledge used by only a few specialists.
