People do talk about the fiduciary duty to maximize shareholder value when speaking generally. They are wrong.
There are only two fiduciary duties in this context: the duty of loyalty and the duty of care. A director of a corporation owes no fiduciary duty to maximize shareholder value.
>>single+(OP)
Sure. I find it easier to use the same words everyone else uses in informal contexts even though there is obvious complexity and is not fully accurate.
>>stevek+pc
I think the point is the term is not so much 'not fully accurate' as 'actively incorrect' and should avoid being repeated as it leads to a false perception of how corporations actually work (or at least, it leads to an inaccurate idea of the origin of their behaviours).