Why do Bosses and above have high resist to pierce?

[Zantai]

I can understand for pierce, but physical? Phyisical is least resisted damage type in the game and it’s quite easy to get -100% physical resist reduction. Making enemies lose the resist to something that they barely resist in the first place, to other damage types that are resisted much more seems counter-intuitive.

Does armor ring a bell? Plenty of enemies have some degree of Physical Resistance, so not sure what you are getting at.