If you bought a jig saw puzlel and some of the pieced didn't fit because they were a scant too large......what would be your reaction.
It is the same with quilting. I assume we all want the pieces to fit. If they fit with the 1/4" seam; the 3/8" seam or whatever then that is ok. However, if I am sewing two pieces together and want them to fit another piece or fit into a more intricate section, then I want it to all fit. The scant 1/4" was suggested to accommodate for the space the fold takes up when pressed. The thickness of the fabric can make a difference; the width of the needle and even the size of the thread. I started piecing some simple shapes recently and changed thread in the bobbin and the pieces didn't fit.....discovered I had put a heavier thread in the bobbin. So the scant is not an urban myth or dictated by some quilt "know it all". It is the reality of making pieces fit If other widths work for you then go for it.