Powdered milk, also called milk powder,[1] dried milk, or dry milk, is a manufactured dairy product made by evaporating milk to dryness. One purpose of drying milk is to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated, due to its low moisture content. Another purpose is to reduce its bulk for the economy of transportation.
Why should I?
Because you evidently feel entitled to an opinion on it.
I learned a long time ago to keep my mouth shut if I don’t know what I am talking about.
https://en.wikipedia.org/wiki/Powdered_milk
What else is there to know?