The problem I have with blogging is the opportunity cost. While blogging may help me as a coder. Does it help more than me actually writing code, or commenting my existing code, or reading an article, or a paper, or spending time reading other peoples code?
I suspect more than anything blogging helps you become a better blogger, and then there are some minor secondary effects. I'm not convinced that if I have zero readers that blogging is the best use of my time.
I started blogging purely as a way of improving my coding skills, and I was pretty cynical about it. From blogging I've had good feedback about how I can improve, and the mere act of keeping a blog has kept me motivated enough to keep learning and keep posting. In my opinion, definitely worth the cost.
From myself (telling the story seems to give a lot of feedback) and from readers. And sometimes the flames of Reddit even contain useful information!
Blogging is definitely not top of the queue, but if I'm going to go to the effort of learning something new, I might as well write some notes on it and the extra effort of putting it into a blog seems worth it for me.
I suspect more than anything blogging helps you become a better blogger, and then there are some minor secondary effects. I'm not convinced that if I have zero readers that blogging is the best use of my time.