If you post a comment hours after I read the original article this morning, I will not remember the contents of the article, especially who said what to whom, after I have taken several business telephone calls and read several articles about various subjects in the interim.

More socially engaged posters will just cite the source, even if it is the original article, but saying something like "it says in the article". Less socially engaged posters will tell other posters to find the source of the quote themselves, as you did.