By the way, I'm not sure why saying "Rejected YC company" is of any value. I don't introduce myself as "Stanford rejected person, Daniel Ha".
Looking at YC-funded companies, I know that they've created pretty impressive stuff. But I have no way of knowing whether they are just kickass hackers who would've created great companies anyway, or whether they became great hackers because of the mentorship of PG et al. There's a selection-bias: the fact that they beat out 400 or so other applicants indicates they were pretty cream-of-the-crop anyway.
By seeing the outcomes of rejected YC companies, we can say "Okay, these folks are drawn from the same pool of applicants, and at least in YCombinator's estimation, they were less promising. Let's see what their success rate is compared to the ones that YC eventually did invest in."
There's still a survivorship bias, because people who were rejected, tried anyway, and then crashed and burned are unlikely to post on news.YC with their postmortems (though I'd absolutely love to see some). But at least it'd give a control group of people who were just as motivated and came from the same applicant population, to compare with the outcomes of those selected for the program itself. Right now, we just have PG's assurance that they roughly double the expected outcome for a startup, with little data to back it up.
When you sign up and add favorite artists the tag cloud then represents your personal musical tastes instead.
The reason for using labeling ourselves as "reject" in this forum, is because There seems to be a large interest in ycombinator companies. Even the ones who were rejected.
We do not label ourselves as this outside of this forum. I also hope it inspires some of the other companies who may not have been accepted as well.