The shareholders literally own the company, so they are the ones who get to decide what gets maximized. Most shareholders decide they want returns to themselves to be maximized. Not all will in every single company at every point in time, but it's likely the case 99.9% of the time.
They have certain claims, but so do customers, suppliers, employees, governments (taxes), bond holders, etc. The claims of shareholders come last, which is why owning stock gets you higher returns (than, e.g., bonds from the company): you're at highest risk of losing money from being last on claims, so you should be rewarded for that higher risk.
Those are opinion pieces and meant to be contrarian. Shareholders by definition own the equity of the company. You're confounding the equity with the enterprise, while also ignoring the meaning of "control".
Having IOUs from the company in the form of future goods or services owed to customers, interest payments owed to debtholders or future taxes owed to the government do not equate to having an actual ownership in the business.
That is one philosophy:
* https://en.wikipedia.org/wiki/Friedman_doctrine
* https://en.wikipedia.org/wiki/Shareholder_primacy
It is not the only one:
* https://en.wikipedia.org/wiki/Stakeholder_theory
* https://corpgov.law.harvard.edu/2012/06/26/the-shareholder-v...