Nobody needs them. That's a ridiculous statement. Everyone is replaceable.
The "E" in CEO is to listen to a room full of noncommittal, hedging, sycophantic people and then chart a course based on their weak signals.
Arguably the CEO needs all of the talent of a dart thrower; but they're the one that takes the stand, or fall, of the decisions made.
I agree they're replaceable. I don't agree that they're not needed. :)
High compensation can be offset by the risk a position entails.
Example: CISOs are feeling a lot of pressure these days