Because all the multiplicative factors from status effects to teases apply only to the player's teases, not tease elemental damage. No enemy uses teases, so they aren't affected by them.
It's the same for Paralyzed, Blinded or Tripped.
Those factors apply before the tease damage cap, which can be easily reached with Sexiness and some Libido, so all positive bonuses barely matter. Only the detrimental ones do. Another disadvantage teases have over lust weapons, like the underleveled factor.
