Dark, that was the idea >.>
She's telling us Suiton + Katon = Futton (Boil Release) while Katon + Doton = Yoton (Lava Release)
Which means the steam ninjutsu that Han, the jinchūriki of the Five-Tailed Dolphin Horse, uses isnt a combination of Katon and Suiton has some ppl thought, although it may still be a Kekkei Genkai.
But you know...I have been thinking...although it may seem obvious that Gaara's sand technique is a fusion of Futon and Doton, how come he doesnt call his technique "sunaton"? Perhaps it's not the "true" fusion of Futon and Doton like how steam wasnt the "true" fusion of Katon and Suiton.
For all we know, that Jinton tech, could be the true fusion between Futon and Doton >.>
EDIT: Thx for the correction Pyro