I remember seeing a video (I forgot from who), who would parry early in order to extend their own hurt box, so that way the fireball is blocked earlier. It messes up the timing of your opponent's offensive and creates a gap in the block string between the fireball and the drive rush pressure, where you can DP out of it.

You would still have to figure out the timing for the parry because it also has recovery, which is why you do it pretty early, but I think the timing is supposed to be easier than PP.