If the underlying hypothesis that overworked developers are bad developers is true (and I believe it is), then it should be a competitive advantage to not overwork your developers.
Hours worked is easy to measure, good/bad developers, quality of code -- not so much.
Doing deep/meaningful work for 70hours a week is reserved for genetic freaks -- 0.1% of the cases -- the rest are either the sub-mediocre bureaucrat types who want the office face time in order to climb the corporate ladder or the victims of the said bureaucrats who are guilt tripped into doing it.