Protection- a polymer sealant forms a molecular bond with any paint surface it’s applied too, so when it’s attacked by environmental elements (acid rain, bird excrement, etc) it provides a direct conduit to the clear coat paint surface, causing surface etching.
Carnauba wax- molecules form a closed linked mesh like structure, which means that they only butt up together to protect the surface and the wax forms a shell like structure that adheres to the paint surface. When attacked by environmental elements they have to compromise the wax surface before they can reach the clear coat paint surface and cause surface etching.
Most organic waxes (Carnauba) are more resistant to environmental hazards then synthetics, although an Acrylic polymer offers limited resistance. Being a sacrificial coating, the best way to avoid clear coat etching is too remove the environmental acid, along with the wax as soon as it’s noticed; but given enough time acid will compromise the clear coat whatever its protection.