Anit synergy with multishot bows?

[SuperSkeletonboi]

lots of people say the piercing arrows (unholy, hellfire, jester) hsve an anti synergy with multishot bows,
obviously there are better choices but why is piercing arrows bad with multishot bows

 

[Capn Fruit Flakes]

Piercing attacks give enemies i-frames when you hit them, meaning the extra arrows won’t deal damage because the first will make the enemy invulnerable.

Take the Tsunami. Instead of firing 5 arrows that all hit the target, you fire 5 but only one deals damage because the first attack makes the enemy invulnerable and the rest pass through without damaging it.

 

[SuperSkeletonboi]

oh