This is an interesting article which makes some good points.
What it fails to prove is that work life balance is a valid concept.
Probably because it isn't.
A key concept is that work is a never ending process. You will never finish. You will never be up to date.
Embrace that and integrate your work into your wider life.
Your partner and family are vital to your happiness.
Your personal fulfillment is also key.
Forget this idea of balance. The aim is to integrate healthy amounts of the ingredients of your life into the time you have available.
I agree that if you are able to leave work "on time" that means you are planning your time well and allocating priorities.
It doesn't mean part time working.
It means plan the work and work the plan.
Over the last 10 years I've constantly heard the wonderful phrase of work life balance, 'Work–life balance is a concept including proper prioritizing between "work" (career and ambition) and "lifestyle" (health, pleasure, leisure, family and spiritual development/meditation)'.