Why profit maxmization is not a primary objective in a firms?

Why profit maxmization is not a primary objective in a firms?
It could be.

But for public corporations, the primary fiduciary duty is to maximize shareholders equity. And, that's done through a number of ways. Profit maximization is one way it can be done... but profits are the result of Revenue - Cost of Goods... and then there's other operating and financing functions before the numbers filter down to the bottom line of retained earnings and shareholders value.

For example, cash flows or financing operations could be more important that simply maximizing profits.