Yah, the bumper reenforcement needs to be cut, you might be thinking of something else...
The bumper reenforcement is that tubular gizmo that bolts to the body, & also is where the lower cladding bolts fasten.
The center section gets enough material removed from the lower run, for the receiver to pass through that plane of being...
Remember when we went to the hardware for 7/8"(IIRC) plastic caps?...
That was to seal the cut ends of the tubular thingy.