If you reject the PWE then very different possibilities emerge and in particular "full employment" stops looking like a good public policy goal and start looking like you're just trying to waste as much of people's time as possible.
I hear the PWE invoked (usually with a sneer), and reflect that it seems to be referring to exactly how my parents have operated throughout their adult lives, and that if everyone behaved the way my parents have done (to the extent that they are capable, of course), society would function far more effectively and harmoniously.
And then I wonder what I'm missing.
My mother spent her career working in hospitals helping to rehabilitate seriously injured and ill people. In her non-work time she cared for her ageing parents until they passed away. Now she helps raise her grandkids.
My father helped design and build telecommunications networks then ran a company making electronic gadgets that helped school kids learn about science, and environmental researchers gather data.
Both of them have spent much of their non-work time volunteering in the community - at kindergarten, school, church, and more. And they have maintained a healthy social life and done plenty of travel.
They've always been busy, but never burnt out or exhausted. Always occupied and fulfilled, never resentful.
I don't see how any of their work or volunteering is surplus to society's requirements.
I do see that society would be better off if more people were doing the kind of work and volunteering that my parents have always done.
What am I missing here?
Probably the religious connection helps illuminate the problem more than it is hiding anything.
The reason this is called a Protestant work ethic is that some Christian sects don't think deeds matter, for them working isn't important, what matters is believing. So a sincere believer who rapes and murders is good, whereas an atheist who is kind and generous is evil. This quickly goes down a No True Scotsman rabbit hole with real Christians, but that's the summary. So the belief that what you do even _matters_ is fundamental to the PWE.
But it turns out that "what you do is what's important" is almost as flawed as "what you believe is what's important". In both cases these rely on a personal God keeping a running tally, they just disagree on what He's counting. But the real world has no personal God keeping that tally, it doesn't exist.
Your parents lives are consequential in their _effects_ not in terms of how much labour they put in to achieve those effects. The PWE quite intentionally doesn't care about those effects, what possible effect could you have next to the will of God anyway?