Not controversial. Just not aligned with the owners of HN.

The comments you upvote/downvote are used to calculate your "opinion similarity" to the owners. Then your upvote/downvotes are modulated by that similarity. It's a way of using other humans to amplify the opinions of the owners -- they don't have time to read all the comments, so instead they filter out those who think the same way they do and let them do it.