Would you rather be hit by a metal bullet or a pellet of minced meat of equivalent weight travelling at the same speed?

Soft flesh causes less damage because the energy is dissipated by deformation very differently on impact than a hard piece of metal.

Try putting a 100 gram piece of chicken (with bones) in your home blender, then try it with a 100 gram RC motor - I am sure you agree the results will be very different.