In baseball and track and tennis, they call mechanics “form”. Think about how that is different from controlling your body muscle by muscle.
When I am being coached in weightlifting, I am told how to move, how to shape my motions, how to hold the bar. I’m not trying to control individual muscles. Certain exercises will aid the development of certain “muscle groups”, and they are executed with proper form in order to be effective. Form is a more holistic and digestible and physically comprehensible way to communicate with the body than issuing a command to an individual muscle or muscle group.