Dopant defect issue

I have used AMSET in my studies and one of the reviewers is having this issue in the amset. I am not able to understand why we are required to change the unit cell to evaluate the dopant effect. As far as I have read we introduce these tags in the settings file. Can you please make these things clear? It would be very helpful in my revision.

AMSET is a very useful package to compute electronic transport properties. The
code includes different scattering mechanism when calculating electron scattering
rates. One of this scattering mechanism is the Ionized impurity scattering (connected
to the level of impurities). However, this code or other codes work well with low midium
carrier concentration. At high carrier concentration (as it is their case)
electronic structure and lattice are modified so, dopants-defects should be included
in the unit cell used for the AMSET calculations. If these defects are not explicitly
modeled in the system, AMSET will overestimate electrical conductivity and power