Good question and simple answer. Why not? If you take a look at the ingredients of your non-natural deodorant, you will know what we mean!
Conventional deodorants contain ingredients that have been linked to issues we don't like.
One study in the Journal of Alzheimer’s Disease found that use of aluminum-based antiperspirants increased the risk of developing Alzheimer’s later in life by 60 percent. Add to that a 2009 study from the University of Reading, U.K., that found a correlation between “the increase in cancers of the outside upper quadrant of the breast with the increase in the use of chemical cosmetics, including antiperspirant” (Gillian Deacon, There’s Lead in Your Lipstick, 2011). Correlation doesn’t always equal causation, but if you have a chance to potentially reduce your risk of illness by changing up your deodorant, why wouldn’t you? (wellinsiders.com)
Natural deodorant contains ingredients that are actually good for you.
Natural deodorants also contain plant-based moisturizers that treat your underarms like the delicate skin they are. Ingredients like shea butter, sweet almond oil and coconut oil can actually improve the condition of your pits, leaving them smooth and less prone to irritation. An irritation-free armpit results in a closer (and longer-lasting) shave. Because natural deodorants don’t block your pores (antiperspirants do—that’s why you don’t sweat), they allow the good bacteria on your skin to work, helping to reduce odor, even when you’re not wearing deodorant. Sweat itself doesn’t cause body odor, but when mixed with the bacteria on your skin, it can stink. Natural deodorants help control the bacteria, therefore reducing (or eliminating) the stench.