I think this misses a huge issue with the internet,

* There is a lot of content being pushed in front of people * There are a lot of click-baity methods/headlines to get people to the content

A tl;dr also distills the article down in a way the headline can't - by delivering a sentence closer to the true content than a headline. If I see tons of articles posted, why should I read tons of paragraphs if the headline offers no clues to what it's about (or is flat-out lying to get clicks). There's only so much time in a day to read, why should it be wasted on shitty content?