Where I've seen pressure advance make a difference is for instance at a sharp corner (like these cubes) where the extruder isn't starting or stopping a line, but is decelerating into the corner and accelerating back out of it. With PA on I've seen those corners go from fairly blobby (similar to your seam) to pretty darn smooth and non-blobby. Note that in the case of corners that are not start or end points the nozzle isn't going to be stopping, just slowing down and speeding up. In the case of a start/end point for a line, the nozzle will in fact stop briefly if it's doing any retraction/z-lift and whatnot, and it's this complete stop for a non-zero length of time that's resulting in that seam.
For kicks you could try this print with zero z-lift and zero retraction and see what happens to the seam. You'll probably get other artifacts that you don't want though (why we have z-lift and retraction...).