It's kind of the opposite of what is described in the article, where the author is using his time off to improve his knowledge in other areas. Personally, I find that back home I am constantly thinking, both at work and in my time off, so much so that I forget what the end goal of all that thinking actually is. So doing these long walks helps me take a break from that and put it in perspective. No laptop, as little smartphone use as possible, I will maybe read a book or two in the evenings but nothing too heavy, etc.
As an aside, I am in a non-tech field, and programming is my hobby (and nothing like my day job). I enjoy it and I think it helps me stay sharp, but it has its drawbacks as a hobby. Being a solo hobby, and not one that many people in my field are into, it's not really something I can easily bond with others over (unlike, say, golf or chess). And sometimes it can be the opposite of relaxing when you encounter a bug that you can't seem to diagnose or fix.