It encourages the 80% into group think. Flagging is a signifier that “you should not dare to think that was a good comment. Move on and don’t think for yourself”.
I expressed that poorly. Just 'boring' alone doesn't warrant a flag.
There's a subjective element.
As an example of something I would flag: a one sentence 'hamas supporter!' or 'genocide denier!' accusation in reply to someone's thoughtful comment. If the same sentiment were expressed in a more original way, I might upvote.
Edit: In regard to news stories, sometimes a story breaks and the main and 'new' pages wind up a dozen links to it. At some point, I might flag that. I'm not sure if that's kosher, but there's little purpose in having users wade through identical articles. Maybe @tomhow or @dang can set me straight if they happen to read this.
>but the apparent reason for many, many flags here is that the content is unoriginal.
Unoriginal to who? What's unoriginal to you might be original to someone else. So your justification for flagging only reinforces the groupthink argument even if you don't realize it.
I've flagged plenty of comments that I agreed with on HN because they were dull and hackneyed.