I think article conflate a lot of complex variables to come to conclusion that it wishes to draw.
It is not just dumb hard work that was regarded as American virtue. In fact Americans are quick to embrace technology to reduce workload, Americans rarely suffer from the luddite attitudes which are pretty common elsewhere in the world. As an immigrant, I think American virtues is about working hard for what you want rather than expecting someone else to do it for you. That notion of hard work is what American society values a lot even today. It is not just dumb work.
I come from India where people think Farmers are hard workers because they work in hot sun where as Tech workers are lazy because they spend all their time in AC offices. I do not see such attitudes in USA at all.
> a recent study found that Americans work 25 percent more hours than Europeans
That also leads to significantly more per capita income for Americans and far better quality of life and not that this is voluntary. Unlike Europe where jobs are mostly "protected" by tighter labour laws, exiting a job is much harder and getting a new job is even harder. USA does not suffer from such problems. I know plenty of people who simply quit their jobs and spend their time doing nothing for few months before getting a new job. No study would put this as "vacation" but in reality has same effect as vacation.
> that U.S. workers tend to take fewer vacation days and retire later in life
This is voluntary too.
> simply working hard doesn’t actually lead to a better life.
This is purely arbitrary conclusion that does not follow automatically from studies that are at best anecdotally.
> I’d argue quite strongly that working more hours, taking less vacation, and retiring later is the definition of a worse life.
May be but this is very very subjective decision and we can not make such conclusions on behalf of other people.