This article doesn't pass the smell test. There is nothing magical about 40 hours per week. 60 hours is just as arbitrary as 40. Also, it probably originated when people did actual physical labor, and so it wont apply to dev work. Countless people in the sciences have toiled day and night to bring about great discoveries - and that's a good thing. Question: Do non-software people (I'm thinking Scientists, Mathematici…
Professors tend to put in roughly 40 to 80 hours depending on their scientific and organisational workload, but most others hardly ever work 60 hours/week with an average of 40-ish. But then, nobody really measures how much time they put in, and you have to keep in mind that in science, the ‘passive work’ done sort-of in the background while doing something else plays a larger role than in programming (at least that’s my impression).
That said, 40 hours is not entirely unjustified, given that 8 hours/day is relatively practical if you want to have both breakfast and dinner at home with an 2hours/day commute and that at least most universities are relatively closed-down on weekends (though some enjoy the much more quiet environment…).