Yes, they will both be drawn from left to right, but the question is about where the decrescendo is relative to the stylus or finger when you first press down. The suggestion here is to have the open part of the decrescendo (the left-most part) be centered on the stylus or touch position. You then drag to the right to stretch it. This allows you to more easily know exactly how it will be drawn, as you line up your finger or stylus to the edge of where the decrescendo should start.
Mike
Mike