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?
I could be wrong. But I can see that interpretation being plausible.
I wonder how often people use OSX's Summarize capability for exactly this purpose. It does a surprisingly good job.
Even a polite request for a TLDR suggests you want to say you read or understood something without making the effort. I might help you fake things like that but only if i really like you, and still feel a little skeezy about it cuz its wrong.
Less polite, more arrogant demands for TLDR (which is how many come across) are worse. Feels like being bullied into helping someone cheat.
By comparison, try this: "I read half of this and am totally lost? Can someone help?" The same question, but the feeling is much different with just a little implied humility.
Nobody is sure which are the best rules to get a nice discussion, but this are the rules here. Other communities like tl;dr.
There are some exceptions, like very very long articles or very very technical articles. Also, sometimes the tl;dr are ignored, nobody is so angry to downvote a tl;dr until it has -100 points. So assume that if you write or ask for a tl;dr, there is a high chance that it will be downvoted.