I would split the hair even finer and say if you're researching how to accomplish a particular task and you serendipitously find an article on HN then you're doing work, but that's pure luck since normally you would be Googling rather than surfing HN. Reading HN "for the [tech] articles" is at best like going to university—you may be preparing for future work, but all this abstract preparation and self-betterment is not the same thing as real work and we would be wise not to fool ourselves.