Shareholder supremacy, frankly, is a very recent concept and is treated as gospel primarily in the Western, English-speaking world.
Most of the world in fact largely rejects it in favor of stakeholder supremacy - which holds that a company is beholden to all of its stakeholders - which means the shareholders, the employees, and the customers.
Indeed, most American and British companies stuck with stakeholder supremacy until the 1970s. Thing is when they switched to shareholder supremacy it actually precipitated a wholesale decline of American and British company competitiveness. This is why West Germany and Japan became economic superpowers in the 80s, followed by China, South Korea, and the rest of Southeast Asia today.
There is in fact nothing superior about shareholder supremacy. Even Western economists decried it as outright stupidity in the 1970s - because in reality its just trying to rationalize uncontrolled greed leading to neverending economic crisis and company bankruptcy.