Because the comment is just a copy/paste of the content at the URL at the top of the comment; which doesn’t add anything to the discussion, because it’s not discussion at all. It’s just a wall of text, it’s not clear to me why you’re posting it as a comment (vs linking to it), and simply regurgitating copy/pasted external information isn’t helpful or interesting.

Next time, write a sentence or two of context about what you’re going to link to — who wrote it and when, why it’s interesting, and how/why it’s relevant to the topic at hand.

There’s almost never a need to copy/paste wholesale external content into an HN comment. Especially true when said content is literally linkable, and actually linked, from your comment!

The reason is that most people interpret the comment as noise. It’s very long, so it takes up a lot of space and makes it harder to find comments by people.

On HN it’s best to just link to the article, no need to also copy and paste anything in comments except for very short quotes.