nepali society is a male-dominated society. women are considered lower to man in every respect. be it inside house or outside, man takes charge of basically everything that boosts their status in the society. whereas women are subjected to the hardship of the household chores and and are basically responsible for the housekeeping works. This is true in the religious practices as well. Though women do puja and worship, it is man who gets the position as priests or pujari or brahmin (whatever). I think nepali society and it's culture is the reason behind that. That has nothing to do with sanitation.