Only the person who posted it knows exactly why they chose this particular day to do so. Probably they came across it in the course of their work and thought it

Only the person who posted it knows exactly why they chose this particular day to do so. Probably they came across it in the course of their work and thought it might be useful/interesting to have a discussion about it. Apparently a lot of other people agreed because they upvoted it. Revisiting old articles every few years can be useful, because the set of people participating in the discussion is likely to be substantially different from those who commented on it the last time it appeared. Those people may have insights or information to share that weren't discussed previously. Maybe some of the people commenting here hadn't even started working in the industry when the original post was made. And even people who were part of the first discussion may have new thoughts on the topic. As an example, while I was certainly aware of and using JSON at the time this article was written, and recall reading it at the time, it is actually much more relevant to me now because I am working on a project that uses JSON in a different way than what I'd done previously. Specifically, we rely on the fact that the same piece of data will always serialize to the exact same string, which we hash and use for later comparisons. We've run into issues relating to interoperability problems between different implementations exactly because of the issues discussed in the article (and yes I'd prefer to use an alternative format for these reasons). This is something I wouldn't have been concerned with at all on previous projects where it didn't matter if there were slight differences. That's just a datapoint on why I personally have renewed interest in this discussion. If you look at a lot of other sites like Reddit (where reposts of articles are often discouraged), you'll often find that on question-based subs, many different people ask the same few kinds of questions with extreme regularity. Subs like /r/askreddit and /r/relationships are full of examples. HN is as much about discussion (if not more) than the actual articles themselves, and as mentioned above such discussions can offer something new each time. So as long as they're not repeated too often, reposts can still have value.