You confused me there, but I see now that it was actually me who confused you as I meant to reply to czzarr instead...
It seems that I helped inspire you nonetheless, which is great of course!
As for what makes tldr.io great; it's mostly the Chrome plugin which adds TL;DR icons next to the links on Hacker News.
They still need to work on enticing more users to contribute back though.
I really like how it uses line by line bullet point fields to help write the summary. I experimented with something like that in the past. It kind of works but it isn't as smooth a read as a paragraph of text but it does make the writing process easier.