My understanding is that that legal case really states that you can’t defraud your shareholders by funnelling money into other businesses they have no ownership in.

It doesn’t set the legal standard that profits must be maximized which is impossible.

Correct, a quote from the linked wiki article: "Dodge is often misread or mistaught as setting a legal rule of shareholder wealth maximization. This was not and is not the law. Shareholder wealth maximization is a standard of conduct for officers and directors, not a legal mandate. The business judgment rule [which was also upheld in this decision] protects many decisions that deviate from this standard. This is one reading of Dodge. If this is all the case is about, however, it isn't that interesting." — M. Todd Henderson

Strange that this misinformation is never corrected.

It technically doesn't. But that's what corporate ran away with and how they justify it. So it de facto did. Shaped a century of labor law around it.