Personally I agree with this to some degree. You get the job done.
The job is never done. Scope expands to fill the time available.
Are all jobs done after specifically 55 hours but not 40? Why not 100?
Finding the right balance between profitability and sustainability is non-trivial, but expected performance is not a given universal constant. It is a matter of experience with a certain level of effort. If expected input was 40h, 'the job' would need to be shaped to fit, just as it has for 55 or whatever.
But that is ignoring all the reasearch showing that for many office-type jobs, the added value of overtime is often marginal or even negative.