Flagged stories get that way because some number of readers "flagged" them, presumably because they felt the story did not meet the HN guidelines: https://news.

Flagged stories get that way because some number of readers "flagged" them, presumably because they felt the story did not meet the HN guidelines: https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html. The ability to flag a story is given after reaching a certain karma level (I don't know the exact amount). So the short answer: because the necessary number of readers clicked the 'flag' link. As to why they choose to do so, your guess is as good as any guess.