This move straight to the throat requires much precision, and the pole can be deflected easily with an arm or the Naginata's pole too. So I say, nothing's for sure, maybe the Naginata's bearer is much more skilled in combat. From what I read, the Naginata was used in swooping moves to keep the opponents at bay; whereas the Yari was used in phalanx, to make a wall of spikes against horse-charging opponents. So maybe the situation we have here didn't happen often.
Anyway, these are nice customs, even if already saw them.
@cheng: Are we going to see some new customs soon? *blink, blink, blink*
A.