One of the things I like the most about HackerNews, and I suspect many (most?) others do too, are the comments. I clicked on the original link curious about why there was not any comments or up arrows ... but will know in the future that it is a waste of time. Why don't they simply add a label like [Jobs available] to clearly identify the purpose of such links?

You can tell by the absence of links to Discuss and Flag the post. I also find these posts a bit odd but HN is YC's sandbox after all, so I can't really complain about them building their own sand castles.