Actually, I sometimes dislike quoting everything. Its unfair if the poster removes the question, or worse, edits it to include info that the responder questioned, that just makes the responder look like an idiot, and the O.P. some sort of martyr -- "Wah, wah, I posted a good full question and they didn't even read it."
However, post after post of quote of a quote of a quote, sometimes just to add, "Yeah" creates a multi-page thread, that answers nothing. Seriously, sort any sub-forum by number of posts, and look at the longest threads. The threads with the most pages aren't the best threads, they're often the worst, as people lose track of what was asked, and what was answered.