How do you see it as derogatory? I'm a native English speaker and have never thought of it that way. I didn't click the link, but did appreciate his short summary – and upvoted him for it. ;)
I also appreciated the summary; my question was just about the phrasing. In it's literal usage, it's saying that the article had nothing useful to say: http://knowyourmeme.com/memes/tldr.
That clearly wasn't the case here, so I was wondering why the author choose to use it. I realize that meaning has changed over time, but I was wondering what meaning he (and others) intend when it is used.
'tl;dr' is often a troll response to a long post that that someone has obviously spent a lot of time on. Bonus troll-points if the long post was in response to another troll.
Example:
poster1: only retards use vi, notepad rules
poster2: huge list of reasons why vi is better than notepad
I was quite peeved when I first saw a "tl;dr" comment concerning one of my blog posts. My thought was, and still is somewhat, "if you didn't read it, how can you say it was too long for what it needed to cover? Why do you feel the need to tell others that you have the attention span of a fly?"
We already have terms like "summary", "digest", and even "précis"; why create a new term imbued with snark?
But not always. You have to consider how it was used to tell whether it was meant with ill will, the term tl;dr on its own doesn't necessarily tell you enough.
That clearly wasn't the case here, so I was wondering why the author choose to use it. I realize that meaning has changed over time, but I was wondering what meaning he (and others) intend when it is used.