Just let it go in one ear & out the other! There are enough "quilt police" out there to populated their own country! Bottomline: they didn't work on your quilt & have no say in how you finish it! Not only is using the backing to bind it economical, lots of quilters actually prefer this method -- it's much quicker than fussing w/ bias binding! One of the quilters in my group likes to leave enough to "double it back" (fold in half to the inside before wrapping over the quilt edge), making the binding even stronger than a normal-thickness of binding would be. Often the wrapped edge is tighter & more secure. Enjoy your quilt!!