This is something that the market can sort out, isn't it? Amazon is famous for being customer-focussed, not shareholder-driven, and they dominate the industries they compete in -- to the benefit of their shareholders. Nobody needs to pass a law telling companies not to focus on short-term shareholder gains if companies that do are naturally out-competed.
Nothing here is "contrary to the theory of shareholder maximization" in any way.
> As such, corporations are best structured and operated with the wellbeing of all involved stakeholders.
Grammar notwithstanding, the same goes for this statement. It is not clear that a focus on stakeholders benefits stakeholders. Maybe healthy, profitable and competitive companies better serve employees and consumers in the long run than companies that directly optimise for those people.