Interesting viewpoint. I'd always assumed that YC-specific "stuff" would get automatic preference, or would at least be marginally sticky. Is that not the case?
While this site does permit random people to submit random links, and then allow more random people to comment on the articles, I'd just assumed it was fundamentally a source of marketing for Mr Graham and his activities. After all, it IS part of ycombinator.com...
I think the preference stems primarily from two factors:
1. There are hundreds of YC companies now, each with multiple founders, almost all of whom are HN readers. Each person here votes on topics, articles and companies they find interesting. I follow a lot of YC-related news because it's fun and helpful to be informed about YC and the alumni. Therefore, I'm more familiar with YC companies and founders, so I will tend to vote on their news slightly more often. With hundreds of founders from YC, it only takes a small bias like this to create a slight lean toward YC news getting better results here than other similar news.
2. This same bias isn't exclusive to YC alumni. Most people on HN familiar with YC like it, respect PG, and are interested in YC companies and the progress of the portfolio. So, in addition to a small bias on the part of the alumni, I have also seen that YC news gets more votes and comments from the rest of the community.
While that might mean that YC news gets more exposure and other news less, more people seem to be interested in it than not, so it seems the forum still works as it should.
While this site does permit random people to submit random links, and then allow more random people to comment on the articles, I'd just assumed it was fundamentally a source of marketing for Mr Graham and his activities. After all, it IS part of ycombinator.com...