It’s not a myth, it’s called Fiduciary Duty. The board, officers, and executives of a public company have a legal responsibility to put the financial interests and well-being of the company above other personal interests. The article you linked doesn’t deny this, and it also isn’t discussing the legal definition of it. It’s discussing what you might call “toxic fiduciary duty”, or more or less the Ferengi Rules of Acquisition. It’s the idea that profit is the primary motive and should always trump all other considerations.
Fiduciary duty is important to create a concrete stance against corruption and misuse of the company’s assets for personal gain. But when taken to an extreme, it becomes toxic and has negative consequences for the company. Employee wages are probably the most obvious example. There has to be a balance between underpaying and overpaying. If you chronically underpay, the best employees will seek more gainful employment elsewhere and the company will suffer from a poorly qualified workforce. If you overpay, like 100% revenue share with employees, the company will cease to make a profit and will be unable to function. A balance has to be struck to retain the best talent in order to drive success for the company; that is the point of the article you linked.
TL;DR extremism is always bad
(Please don’t mistake this for a pro-capitalism rant, there’s nuance to be had here)