First of all, I've been told there is no such thing as a dumb question on this board - to which I say whew!
In home-ec classes I learned the same thing and although I've barely sewn much since then until lately, I can still hear that rule dancing in my head. It's a hard habit to break. Like others have said, I have slowly come to realize that in most cases, there is rarely any need to lock or back-stitch in piecing my quilt-tops - I will probably backstitch on the borders.