Everything that didn’t happen is speculation, so that is no argument. The German troops did not have the proper gear for months of marching. They ran out of supplies due to overextended supply lines. That is not speculation. The advantages of short supply routes, familiar terrain, and more well-rested troops is also not speculation. That the western front was far less well protected due to the much larger eastern front due to Barbarossa is also not speculation nor that moving troops between the fronts was far more costly (time and material) due to the distance into Soviet territory the Germans had to travel.

We’ll never know, but logistics is definitely on my side of the argument.