Is there a specific reason for this ? As in, does the 3DLut generated later take care of all tone adjustment, Such that this tone curve portion of the calibration is unnecessary ?
Correct, the 3D LUT does take care of everything (thus the separate tone curve choice on the 3D LUT tab), so time spent creating 1D LUT calibration would essentially be wasted. The only reason to enable 1D LUT calibration is if you also want to install the resulting profile, and have non-color-managed apps benefit from at least having neutral grays and following the chosen tone response. For madVR, it’s not relevant.