I think CEOs are there to simply not screw anything up.
In other words, they were picked so that there wasn't someone else there who would screw up more.
They are supposed to be quiet, run of the mill, go with the flow kinds of people. This is the implicit requirement. The explicit one is, "just keep the overall revenue growth stable".
There is no requirement about "solving existing issues" because that's not part of "the bottom line" or even to land any "big wins" because growth is already "good enough" and it's better to maintain it, than risk it and lose everything.
Why this profile for CEOs?
These days, everything is amplified and the smallest mistake can mean big trouble. Top leaders are already magnets for attention due to their role, and if they start to make noise about anything even minor, it will be bad attention.
If the business is already good, "let's not screw anything up".
That's what I'm thinking. I feel that this applies to Pichai, Cook, Nadella and others like them [1]
The danger could be that the companies may become complacent and get disrupted eventually. But perhaps that is something they watch out for (maybe another part of the JD) – and they buy out any competitors that get too haughty, as needed.
[1] Zuckerberg is an outlier because look, he's still a founder CEO unlike the others, and that's because, no matter what you think of him (or even if he's a robot ;) ), he has a terrific track record in decision making. So he's there and allowed to make decisions, even high risk ones, such as the whole Metaverse invention or the stuff about culling headcount "who shouldn't be here". Though he's also doing those decisions due to privacy regulations which seems to affect the stable growth mentioned above.