Here's a video example of small amount of force doing more damage: Listen to the sound of the impact. The one that hurts me the most were the punches that didn't make a sound. Small force doing more damage. If we go by your theory "the least work to generate the most force" then those slower and softer punches would not have hurt me. With that particular punch, a significant amount of damage can be caused without requiring a lot of force to do it. The video was part of a clip that recorded our conditioning classes. If I were to show the class version then you would see me barely punching the other guy yet his responses are as if I was throwing punches as hard as possible.
In martial arts large amounts of force is not always needed in order to cause damage. Your understanding of force does not take into consideration damage. It only take into consideration "hit harder." However, martial art techniques will often take into consideration damage. It doesn't look at how hard I have to hit someone. It looks at where, when, and how I can hit someone to cause the most damage. Most instructors will tell you to focus more on technique than power. Technique first then power. Not Power first and then technique.
See video. Punches were not thrown at weak points like the groin. They were thrown at the same are where people take body shots.
Boxers break their hand all the time and they wear gloves.
It doesn't bother me. Let me know what you think of the video and no it's not fake. It took me about 4 months to heal from those punches that he did with technique.