Yes, I believe you're interpreting that page incorrectly. Fiduciary duties are law bindings for specific relationships and situations not applicable for all publicly traded companies to all shareholders.

I believe you're confusing that idea with the theory of shareholder supremacy that's a claim, popularized by the likes of Jack Welch to support their actions.

The background comes from Dodge v. Ford Motor Co. in 1919 which stated

There should be no confusion... A business corporation is organized and carried on primarily for the profit of the stockholders.

and the interpretation has been quite debated.