Bad article, in part because of the incomplete title. It should be called "What happens when your career becomes your whole identity, when you don't like your job and think it's a waste of time". If this latter part is not true, there is much less of a problem, but for some reason current mainstream American culture wants to extrapolate all the way to "work should be compartmentalized and minimized".
The problem is, work is where a lot of people find meaning in life. For those people, more work means more meaning, and you're hurting them by telling them otherwise, especially if they are too young to know better than what you are telling them. And you're also preventing young people from becoming outliers ... what would be the cost to our society, and to the individuals personally, if Einstein, Dirac, Pauli, or whoever had been told to cut down on the amount of time they spend thinking about physics stuff, they need to achieve good work/life balance.
A lot of people in China are working pretty hard. If you want your country to get whomped by China economically and geopolitically, spread the idea that it's bad to work hard.
Americans in the past, back when America was able to coordinate to do ambitious things, worked pretty hard. So if you want to have a country that is unable to recreate glories of the past, spread the idea that it's bad to work hard.
All this only happens if you have an idea of work as a draining thing, a net negative on the individual doing the work. But I am happier because of the work that I have done. I am a better person than I was before.
Nobody goes to the kung fu school and says "hey it's bad to exercise this much, you shouldn't kick so high or punch so fast, just make sure not to train that much, okay?" But for some reason we have decided it's okay to give people this advice in other realms. You know what, I never felt as good physically as I did when I was in serious kung fu training. (Never looked as good either).
If you are in a job that actually is damaging if you do it too much for too long, then by all means, minimize that -- but you know what, in today's world, there are always proximal things you can do that are not damaging that will improve your job or your ability to do your job over time.
But advice like this does not make the distinction between jobs that are damaging and jobs that aren't. We're losing the idea that the latter thing exists, and I think that is very bad for the overall development of our society.