The idea that execs of public companies have a legal requirement to maximize profit for shareholders, which is false and based on some misunderstandings of actual requirements, has been frequently stated (at least by commenters and pundits) as justification for companies taking awful and inhumane actions. ("Frequently repeated" makes it a meme; the word doesn't just mean image macros.)
The "fiduciary duty" rule that actually exists simply means (as I understand it) that execs can't legally enrich themselves at the company's expense beyond their agreed-upon compensation, without the approval of shareholders/the board.
So no; "every for-profit company" should not and does not have to take steps to maximize profit at the expense of their employees, their customers, and the public at large. Frankly, many of the ways they currently do this either are already or should be illegal, and are definitely immoral and detrimental to a healthy and functioning society and economy.
They only have to do what the shareholders demand if the shareholders actually vote to make them.
The meme of the "fiduciary duty" meaning that profit must be maximized at all costs has been debunked so many times by now it's really not funny.