On Tue, 7 Oct 2008, Wilhelm Schnotz wrote:
We already do have in a way quality warnings, all the editorial warnings at the top of articles in a way say this article is still in progress. (those that say more sources needed, copyedit needed, etc).
We also rank articles by "quality" when wikiprojects do their article classes. In theory an "A" class article is better then a "B" class article, etc.
By the same reasoning used for spoilers, we don't have a source which states that an article needs copyediting or that it is class B. (Remember that Wikipedia itself isn't a reliable source.) Making that decision ourselves is original research.