When people say this, they usually mean that HN is all in favor of X where X is something they personally disagree with. In fact, though, the community is divided on most issues. There are a few exceptions (anti-Snowden doesn't do well here*, pro-CFAA worse) but not as many as it seems.

I think this impression of 'the community lined up against my view' happens because when you read HN threads on any divisive topic you're inevitably confronted with comments you dislike and disagree with. That follows simply from the community being divided while the site content is all in common, i.e. non-siloed - no subreddits into which people partition themselves.

Such comments are unpleasant—indeed painful—to read, and therefore more memorable, so we notice them more. These impressions accrete into a mental model of the community all being on the opposite side. But this is actually a side effect of the site not being homogeneous—of the fact that for most X, everyone who feels strongly about X has anti-X comments in their face, and vice versa.

* Edit: this eventually changed.

Where did the parent comment imply that?