People who knee-jerk to typing, or even thinking, the phrase, "TL; DR" are lazy and undisciplined.
There I said it. I'm not sorry if I hurt any precious feelings.
"TL; DR" is a phrase designed by lazy people to irritate more disciplined people. It's basically people bragging about not having the discipline to read something, and simultaneously wanting to let you know about it.
It's also very smug. I compare it to people who shrug off the fact they don't know something they should know by saying, "Naw man, I don't know that shit! haha."