I always thought there was a reason that no downvote option was offered on submissions, i.e. so that people wouldn't bury articles simply because they didn't agree with them, etc.
Instead it appears that people are using the flag feature to do the very same thing. This is actually worse than downvoting, because if a submission gets enough flags it just gets killed outright. At least with downvoting, it just effects the point count, which I use as a shorthand to decide whether an article is worth reading or not.
I have only every used the flagging feature for articles that were completely inappropriate for Hacker News (e.g. stuff about politics, jokey stuff more appropriate for reddit, outright spam). I would never dream of using a flag to register displeasure with an author's style, arguments, choice of title, etc. as other people are suggesting here.
Maybe I'm the only one who feels this way, but I find it disappointing that people use HN like this.