I think it's harder to agree/disagree with the typical headlines featured on HN. Most articles on HN appear to be straight.
But let's say that two articles were in the queue, one pro-X, the other anti-X and the pro-X forces were dominant. Sure the pro-X article would hit the FP, but the anti-X forces would still comment on it and be down voted.
Also the bias is only visible in the comment section because down voted comments remain visible, whereas a down voted article gets flushed down the memory hole.
But let's say that two articles were in the queue, one pro-X, the other anti-X and the pro-X forces were dominant. Sure the pro-X article would hit the FP, but the anti-X forces would still comment on it and be down voted.
Also the bias is only visible in the comment section because down voted comments remain visible, whereas a down voted article gets flushed down the memory hole.