Nothing Natural about "Natural"

Whole body movement is not how we like to move. Like most people, you probably didn't get lessons on how to move. One day, you didn't fall over when you sat up. That worked so well, eventually you didn't crack your skull standing and then eventually you threw all caution to the wind and moved your feet. Whether or not you moved effectively or smoothly was mostly an accident. You might have been teased on the school yard, or taken a dance lesson or joined Junior Miss pagents or something that made you pay attention to your walk.  Your first pair of heels maybe, or an injury.  Walking was not likely judged for it's effectiveness - the only standard was, "don't fall over most of the time."

In keeping with the Tandoku theme, the idea of feet only movements, then simple one step movements with one hand in motion, then increasing the difficulty in the feet, then increasing the difficulty in the arms and eventually using two arms with the more complicated footwork - this formula is something I see in Taiji push hands progression as well.

Isolating a body part to move it, then isolating another body part, then slowly complicating the whole thing - now, the whole body is being used.

The video above shows a series of Chen exercises, and a nice progression.  Few students get past solo form, and those who do get into paired work often stay in the early phases.  Basic push hands is where power and neutralization is expressed in the hands, and the feet are locked in place.  The waist and the weight shift is the driving force.