I would think this would only be an issue if inferior quality fabric were used and therefore affected the finish of the piece - in my experience, cheap fabric (and I mean the quality not the price) can lead to distorted seams, puckers in the quilting etc. If I'm making a quilt for a competition, I want to do the best job I'm capable of otherwise what is the point of investing my time and effort? Therefore, I wouldn't use sub-standard fabric.