This asana seems giving strength to arms only but like other asanas this asana too engage other body parts. It strengthens abdominal organs as without core strength it would be impossible to perform this pose. Other body parts which are also significantly engaged in this asana are thigh muscles. So, performing this asana is engagement of majorly arms, core and thigh muscles. By this it benefits them all. By engaging core, it benefits all abdominal organs. Thigh muscles also become flexible by regular practice of this asana.
In life also same thing happens, we believe if I am the only responsible family member who is making the family run become it looks so from top or prima facie. But like in above asana, there are other family members too whether spouse, parents, kids or siblings who make your family sun successfully. They may make their contribution silently but significantly. Same rule applies at workplace too.