It is to some extend. But the mash pH is generally determined by what is good for the amylase enzymes. Aiming for a mash pH between 5.3 and 5.6 will also give you an adequate pH for the protoelytic enzymes.
The protoelytic enzymes are most effective between 4.9 and 5.1 but that is already too low for good starch conversion, hence the recommendation to aim for the pH necessary for the amylases.