Earlier than that

IV: Rosa, Rydia, Porom
V: Lenna, Faris, Krile

But then again, this might not be exclusive to FF. Chrono Trigger has Marle, Lucca and Ayla, Xenogears has Elly, Emeralda and Maria, Xenoblade Chronicles has Sharla, Melia and Fiora, Xenosaga has KOS-MOS, Shion and MOMO, both Persona 2s have it (Maya, Ginko, Yukki / Maya, Ulala, Elly), etc. etc.

It's a thing. Funnily enough, it's even present in EoFF's very own fan game, Death of a Fansite, so you could just ask Psychotic

Pretty sure it's to meet a quota. Just enough to not be considered pure tokens, not enough to be """"too girly for boys to enjoy"""".

They're also there to fill archetypes. As Jinx herself put it best, regarding DoaF, "Pumpkin the cute one, Shauna the mom, Freya the whore".