Ask HN: What's wrong with asking for a TL;DR?
I think there is a legitimate value in short summaries of long articles. Often you can extract 90% of the value with just 10% of the time (and more importantly 10% of the energy). I'm mainly reading articles on HN to extract value, not because I enjoy the experience of reading.
Also, a summary can indicate whether it's worth it to read the full article. When it's unclear from the title what some heavily upvoted article is about, should you spend the time to find out and risk wasting some of your limited time and mental energy?