This is exactly the attitude everyone is challenging.
This is the superman myth, it doesn't exist.
If Bob, our intrepid entrepreneur, actually worked 40 hours a week he wouldn't spend so much time faffing. The 'busy work' disappears. Overall productivity drops the more you work long hours.
I've nowhere near your experience with entrepreneurs, I totally admit, but one of the symptoms I've noticed in crunch entrepreneurs is their mental diarrhoea, they take 15-20 minutes rambling on talking to you about a decision you've asked for that they normally would have made in a minute or 2. You start walking away and then suddenly they have another point/thought. They're mentally exhausted. I can reflect back on myself and see the same thing when I was doing crazy hours.
Some of these people have succeeded, some haven't.
But the person them self doesn't notice. They still think they are operating at high productivity.
I don't know. It seems you are confounding a couple of issues. First is the scope of the article. It seems more of a policy for good practices to adhere to in treating employees. Even if you are a marathon runner, it would not be in your self-interests to require long distance running as a job criteria. Secondly is motivation. The motivations of a founder are often counter to that of an employee. From the perspective of many employees, job satisfaction is much more desirable to a high reward outcome - irrespective of dedication, hard work, or talent.
While you know your experience, you don't have access to the alternative futures that might have resulted given different behavior. Which is why personal experiences and anecdotes do not substitute for actual causal analysis.
At a certain point (or at multiple points during a suitable long stretch), enduring the long hours becomes a top priority for an individual actor in an attempt to avoid the "slow-down". The actor may decide to switch to a task that they can more easily handle so as to remain "productive", but this switch is not necessarily to the most important task to complete the enterprise goal; or may be a "refresh task" which does not directly contribute to the enterprise goal (though may help with the productivity on future tasks).
As a result, they see high productivity, but do not see the focus shift. Staying on task is what is important in crunch mode, and there may be some utility to founders that have more tasks (and thus goals) in shifting focus, but larger organizations suffer from defocusing, task shifting, and worker collisions.