I think there is a happy medium. Lately there have been a lot of discussions on the Modern Quilt Guild Blog and spinoffs regarding influenced and derivative works. Unfortunately in the quilting world it is very hard to draw a standard line. And the shows don't want to do so because they might have some liability if they do. If they don't ask, then the liability probably rests on the entrant (i.e. they dont' have to do any verifying). Is it right? Not if you are someone other than the entrant.
That said, I do agree with the OP that quilt shows should request all the information - designer/inspiration, piecer, quilter, etc.