This one's easy, because patterns don't guarantee anything. They don't even make benefit likely . Patterns do nothing to remove the human from the creative process. They merely bring hope of empowerment to a possibly inexperienced, perhaps merely uninitiated, but otherwise capable and creative person. That can only occur if the pattern strikes a chord in the reader's mind.
Patterns are just another weapon in the developer's arsenal.
To ascribe much more to them is counterproductive. This misconception is like unto the last one, except that it's less aggressive in its overstatement. The generative aspect of patterns gets discussed periodically in the pattern forums. That's a fancy way of saying the pattern helps the reader solve problems that the pattern doesn't address explicitly. Some of what I've read suggests that true generativity makes this happen almost in spite of one's self.