"But I don't subtract 5 minutes from my "time spent working" when I check Hacker News while my code is compiling. Am I being productive? No. Am I working? Yes."

I would count reading HN as inspirational and thus inclined to lead to better/more productivity/idea's etc. I can count numerous things on HN that lead me to being a better dev. I also used at a lot of interesting tools/tech that came up on HN and that would later fit/solve certain business requirements. So this surely did make me more productive. I would say though this depends on your ability to filter, scan and retain information derived from articles that are often tl;dr.

Also this article in itself is misleading, so reading an article posted on HN on how to be more productive is not considered productive?