"at the head" of large - especially publicly traded - companies is not the same as trying to run all aspects of the day-to-day. It also rarely (ever?) happens when they don't have a big ownership stake, or are there primarily as a figurehead.

We can debate if the executive timeline is too short and that's what destroys companies, but I don't see how this is the same as an over-employed engineer who's spread too thin.

Many would argue that, indeed, said public CEO is spread too thin.