One of the main functions of leaders (should be) is to assume responsibility for decisions and outcomes. A computer cant do that.
And finally why should someone in power choose to replace themselves?
Sure it can. "Assuming responsibility" just means people/the law lets you to.
It can be totally empty too, like CEOs or politicians "assuming responsibility" for some outcome but nevertheless suffering zero conseuences.
Firms tend to follow peers in an industry - once one blinks the rest follow.
Alas, shareholder value is a great ideal, but it tends to be honoured in practice rather less strictly.
As you can also see when sudden competition leads to rounds of efficiency improvements, cost cutting and product enhancements: even without competition, a penny saved is a penny earned for shareholders. But only when fierce competition threatens to put managers' jobs at risk, do they really kick into overdrive.
It's one of the most horrible ideas ever, responsible for anything from market abuse and enshittification to rent seeking and patent trolling.
Since the board of directors can decide to replace the CEO, it's not the CEO who holds the (ultimate) power, it's the board of directors.