With regard to tl;dr's use in comments, I've only ever seen it used in a sarcastic, joking manner - say someone gets overzealous on a subject, or gets wanky for more than a paragraph, 'tl;dr' is used as a friendly mock to remind them to keep on track, or to halt some wankery in its tracks. Which is why I was surprised to see your rantage - I've simply never thought of the expression in a nasty way.

Ah well, maybe I've just been lucky. :)