[onreact]

Sure, some people can work longer than others but they also may get sick more often then. A friend of mine used to work 10h/12h and then game at night but was chronically ill with his skin. It only really got better when he went on vacation.

The 40h work week has been introduced by Henry Ford 100 years ago because even in factories with dumb menial work people were getting tired and breaking more than making after 40h.

In creative industries that require programming, graphic design, writing etc. you can't assume that people will be doing good work for as long as factory workers do who only have to focus on the same repetitive tasks.