The rider's movements are the key for handling the off-road model. Therefore, the area within a 500-mm radius of the foot step has to be clear. It is crucial to lay out the parts in this area so that they will not block leg movement. This is an important technique for the off-road model design. This 500-mm radius defines the area where the leg, or more precisely the knee, moves around.
Oh, you are right. I didn't notice it until it was explained to me. Riders get really uneasy off road when our bodies can't move freely. I can be sure my legs won’t interfere with anything. So, this is the function the off-road model design offers.