You can get pretty close with multiple measurements and a 6th octave smoothing (which is psychoacoustic in nature) except for the time domain correction which I think is Dirac’s secret sauce. However you also can use DRC and DRC Designer or Rephase to achieve some level of time domain correction on the averaged measurments. It is free and you can get filters that can be used with Roon (Digital Room Correction)
You are right Dirac uses some form of position-independent correction especially to the excess-phase component and that results in better results.