One hypothesis: reading is a concentration-building activity. One of the greatest determinants of success as a software engineer is your ability to attain and maintain concentration. If this is a habit for you, you're going to be a better programmer.
Contrast with the more typical leisure activity (of which I am totally guilty): the Skinner boxes of HN, Reddit, Facebook, and to some extent Netflix.
Contrast with the more typical leisure activity (of which I am totally guilty): the Skinner boxes of HN, Reddit, Facebook, and to some extent Netflix.