Glycerin is a natural byproduct of the soap-making process (saponification), and it is a genuinely good thing for skin — it is a humectant, meaning it draws moisture in and helps skin hold onto it. Traditional cold-process soap keeps this glycerin in the finished bar. Large commercial manufacturers, however, often remove it deliberately, because glycerin is valuable on its own and gets sold separately into other products, from cosmetics to pharmaceuticals. What is left behind is a harder, longer-lasting bar that is cheaper to produce at scale, but noticeably more drying on skin than a bar that kept its glycerin — a real problem in Australia's drier inland regions especially. This is the real, practical reason traditionally made soap tends to feel gentler than a supermarket bar — it is rarely about "chemicals" in a vague sense, and much more specifically about what has been taken out.