What aligns the golf club?
In the golf, swing rotation is what makes the club seek alignment. As soon as this rotation is stopped, the club will move out of alignment.
Understanding rotation and how it aligns the club is why we need the club coming down behind our hands.
The inside path allows the body to rotate, which in turn aligns the club into impact.
KISS: I am going to leave it as simple as that so you understand why we shallow the club in the downswing.