IIRC, Patrick has said that posting interesting technical content to get links to his site was part of his promotional strategy for Bingo Card Creator. For example, that's why he hosts A/Bingo there even though there are very few elementary school teachers interested in split testing their websites. Even more to the point, he actually publishes his entire sales and expense data for the product at http://bingocardcreator.com/stats, which is likewise quite uninteresting to his customers but catnip for the HN crowd.