It is so rare because it is pretty useless, inefficiently and there is no need for it in the proposed regions. People there desiccate their food or use spices l

It is so rare because it is pretty useless, inefficiently and there is no need for it in the proposed regions. People there desiccate their food or use spices like chili to make sure it stays esculent for a longer time, They don't have much water, so in my opinion it is pretty stupid to waste it for food if they have much better ways to conserve.