I watched a strawbale building demonstration 20 years ago where they torched a stuccoed strawbale structure that had no treatments: the fire reached over 2000°f and when it was cooled, they cut open the stawbales and showed the fire didn't burn the bale more than an inch deep. They really do not burn due to the lack of oxygen.

Water on the other hand can rot out a whole wall if it's not sealed.