The stub shaft can be made independent of the widening mod. As you raise your ride and adjust Diff drop to get every set in right spot it makes changing out the ps CV's a much simpler job. If you look at your CV shafts, they are slanted towards the back of vehicle. So when you move the back hole of the A-arm mount outwards, it moves the ball joint forward and outward (in an arc, it is a triangle).
This outward move is somewhat canceled by straightening the CV, so it is not slanted backwards as much, and the reason for using the extra flanges.
If you make the stub shaft getting the shaft length correct is very important, as it ends up really close to the diff mount bolt heads. I have heard of some using counter sunk bolts to keep clearance between the diff mount bolt heads and the CV shaft bolt heads.