Why does C1 require light fall-off adjustment for panos

Over the years I have stitched numerous panos with: Hugin, Affinity, Photoshop, Lightroom, C1, Ptgui and nobody but C1 requires a separate light fall adjustment. And by the way, the required setting of 100 is not always the best, I usually have to fine tune the fall-off setting by iteratively selecting a setting, stitching and inspecting the resulting image and then repeating the process to remove banding in the sky.