Our simulations predict that the cumulative effect of partial solvation and IEF cannot promote the DA reaction in water microdroplets. In fact, the barrier of the modeled DA reaction is higher at the air-water interface than in the bulk and this barrier is only slightly lowered under uniform external electric fields. Moreover, the IEF at the surface of water microdroplet is found to fluctuate continuously, a circumstance mitigating the overall electrostatic catalytic capability carried by the field. Microdroplet experiments with water and acetonitrile independently affirm these predictions and find instead that confinement effect and the increased concentration driven by evaporation are the key factors that increase the rate of the DA reaction in microdroplets. We would like to point out that the "confinement" in microdroplets, unlike the nanoconfinement, where length scales approach molecular dimensions, it refers to microconfinement, where the compartment dimensions encapsulate a relatively large number of solute molecules. This confinement limits the Brownian dynamics of reactants, thereby enhancing the frequency of bimolecular collisions necessary for reactions, be it on the surface or in the core. Recently, Wilson et al. introduced the term "kinetic confinement" to describe this effect in microdroplet reactions. This work elucidates the nuanced role of microdroplet interfaces in chemical reactivity, offering insights into optimizing reaction conditions for potential synthetic applications.