I would say that's more prevalent in HN. A lot of the "Who's Hiring" posts are veiled show-and-tells. Some of those companies clearly have no intention of hiring. Even got an automatic rejection email from one of those (within a minute of applying). To be fair, it does work - I've discovered some interesting startups and market niches from the Who's Hiring threads.
As an opposite data point, when I was looking for a job I interviewed with multiple companies that I found on HN who is hiring. And one of them ended up hiring me. Two years later I work for them still.
