Because body-building is an art form, not a form of exercise. I have worked in physical jobs that require overhead lifting (for example) and, regularly, scrawny

Because body-building is an art form, not a form of exercise. I have worked in physical jobs that require overhead lifting (for example) and, regularly, scrawny-looking guys have to help out their body-building cow-orkers, who just haven't developed the ancillary muscles that provide control and balance, because that loses "definition" (or whatever the term is).