The opportunity to develop perspective and taste when it comes to programming languages, libraries, and paradigms. I read "Can programming be liberated from the von Neumann style?" for the first time because it gets posted to HN every couple of months (the mods should automate it at this point.) I've seen a steady drip of interesting discussions about and debates among proponents of lisps and statically typed functional languages -- and at the same time I witnessed the fall of Rails and the rise of one hot Javascript framework after another. If it weren't for HN, I'd still be blaming myself for not doing OO right, instead of coming to understand that OO is metaphor rather than science.