On PLD, Block takes precedence over Parry, so if a Block and Parry are happening, Block will happen, not Parry. If your Block rate is high enough on your shield, you will block lots and parry very infrequently. Given your Block rate is determined by your shield and dexterity tier, and Parry by the rest of your gear, and we cannot Parry magic damage (which is the only type of damage SCoB does) but we can Block magic damage, it makes sense to forgo pursuing Parry on a PLD. PLD has plenty of damage mitigation without parry, if you have a good shield, high strength, and know how to use the buffs. Might as well just look at DPS stats over Parry.