I'll keep saying it: HN should have a short abstract (aka tl;dr) attached to each article, written and updated by user submission like comments. Maybe minimal GitHub-like version control with pull requests accepted by vote.
The abstract would be more valuable than comments, so accepted modifications could get extra karma.
https://www.reddit.com/r/geopolitics/comments/3yh1ll/introdu...
https://www.reddit.com/r/TrueReddit/comments/1p4gqg/new_poli...
Note that there is no support by the reddit software, so this just shows up as regular comment and can't be edited by the crowd. I'm still impressed that enough folks have recognized the value of the general idea. (Too often, asking for a tl;dr is considered ADD/low-class/impatient/etc.) And it also emphasizes that this could be useful not just to save time, but also to keep article quality higher, if submitters are required to justify the intellectual value of the submission.