1) Work life balance is about employee long term retention and places like Google spend a lot of energy in hiring, so they optimize for keeping the people they hire.
2) Sometimes an 11am yoga class frees your mind enough to foster creativity. Raw working hours may be reduced but novel solutions might increase.
3) Some tech workers have figured out the odds of hitting it big in a startup or having the next billion dollar idea are not that likely. Instead, they've optimized for a far above average salary with work life balance. There is nothing wrong with choosing that path and this is where the author is missing empathy for people who didn't choose his path.