Not as advanced as a stop hit but more effective than blocking and counter attacking in sequence.
This is also practiced by some Chinese martial arts.
Simultaneous parrying & punching utilizes the principle of economy of motion by combining attack and defense into two movements thus minimizing the "time" element and maximizing the "energy" element.
Efficiency is gained by utilizing a parry rather than a block. By definition a "block" stops an attack whereas a parry merely re-directs an attack.
Redirection has two advantages: It requires less energy to execute; it utilizes the opponents energy against them by creating an imbalance.
Efficiency is also gained in that the opponent has less time to react to the nullification of their attack while having to worry about defending an incoming attack.
