I think the work-life-balance was invented for those who are in conflict with their job, or who do not enjoy their work.
"You need a change in your life" so they get a divorce. Even though their partner isn't the issue. Rather than working out what is causing their suffering internally, they look for an external scapegoat.
I see it rather as phases of priorities, necessary ones.
And a person can be supremely happy, working their ass off, if it is for the right reasons. So is the workplace the issue, or the person choosing to work at something they care little about?
I don't think everyone can choose their work, at least here that's not really the case. But there's the ego-part, too, many people believe themselves to be made for something better (which sometimes they are, but mostly not). My grandpa always said that one can have fun in whatever, if you really put effort in it. That didn't work for me, at least. But as I said, I believe that it's phases. Sometimes we have to bite the sour apple and work ourselves out of it, until we're in a position for a better job (through qualification, studies, whatever).