I think that saying was created just for writers.
When you're waiting to hear from an editor or an agent about your submission, "there's still a chance," as Ginger said in Chicken Run.
But when you get a reply, and there's a 90% chance - on a good day - that it's a rejection, then, really, no news is good news. Or, at least, better news.
"There is no such thing in anyone's life as an unimportant day." – Alexander Woolcott