It's implicit that the submitter of an article thinks it's worth reading. It's not implicit that other HN users think it's worth reading. Again, HN receives a n

It's implicit that the submitter of an article thinks it's worth reading. It's not implicit that other HN users think it's worth reading. Again, HN receives a new submission every few minutes. Not every article is worth our time; there's not enough time even if they were. Thus, the point of the summary is for the submitter to explain to other users why the article is worth reading. Moreover, HN submissions are on a very broad range of topics, so even if an article is worth reading on a specific topic, readers are not interested in every topic. Some article titles are so vague that you can't even discern the topic!