To me, going on holiday, learning the guitar, writing fiction, sleeping, etc. are all also part of my work/purpose, which is multi-faceted and not contained in a single job description (not that I have one of those).
There's a saying that "sleep is when you work with your eyes closed". How many brilliant work-related answers and solutions have you come up with while sleeping or in the shower? Obvious conclusion: your ability to sleep, take showers, and do other things that "recharge" your mind is not something separate to your work, it is crucially important so that you can actually do good creative work, rather than just bashing out mediocre widget after mediocre widget. And pretty much everyone on HN does what Schmidt calls "smart creative" work.
And there definitely needs to be a two-sided trade-off between organisation and employee in this: if the person is expected to be effectively "working" (i.e. considering work-related topics in the back of their mind) at all times, then the organisation needs to recognise that and not impose ridiculous restrictions like fixed working hours and workplaces. As Ricardo Semler puts it, we've all mastered the art of checking our work email on a Saturday evening, but few of us have mastered the art of going to watch a movie on Tuesday afternoon.
Please note that no company will, imho, be able to develop such a culture without it turning into a manipulative scam unless the people who are trying to create this culture actually genuinely care about people, rather than just pretending to care. I've covered that idea in this article: http://danieltenner.com/2014/07/31/you-cant-hide-from-yourse...