If I understand correctly to seal up the bearing area while allowing the CV not to turn. Having machined flanges along with the dust cap will prevent contaminants from entering the bearing area and prevent grease from escaping.
I looked at doing the same thing but decided against it. My thoughts - The spline supports the outer end of the stub axle shaft and in order to remove enough material to keep the axle from coming in contact with the drive plate the edge for the cap was gone. Also the snap ring on the axle end keeps the rear seal tight against the wheel without the clip dirt will enter. I saw it as a no win.
Your thoughts?