This rule has always been there, just not written down because we thought you'd know what quality control is, but apparently some of you don't.
Topics containing "art" of extremely poor quality can be locked/disposal'd and under some circumstances be counted as spam, which is a warnable offense.
You should know what is and isn't acceptable here through common sense alone. But if for some reason you don't, having your topic locked should be enough to show you that your art is not acceptable. Afterward you will be held responsible for your actions here.