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?