People who palm aggressively while manoeuvring,why?

Just curious and of course directed at auto drivers.
Before I learned to drive one thing I noticed was how some of my mates and other drivers would palm aggressively (if that makes sense) especially while reverse parking or moving back onto the curb.
Now it’s been a while since I have started driving , I am just not able to figure out what are those people trying to achieve when majority of the time the same results can be achieved with subtle movements of the steering wheel.