Rule 4-3, Damaged clubs: Repair and Replacement

[Johanna]

Despite the heading of Rule 4-3, nothing is said in 4-3a and b about repair and replacement.
Your Rule 4-3a allows the player to continue play with the damaged club but 4-3b forbids such. Why the keep the difference as in the present Rules? Would it not be simpler to allow play with the damaged club in both a) and b) circumstances, but only allow replacement when a club is accidentally damaged as in 4-3a?