The structure and dielectric properties of the electric double layer (EDL) play a crucial role in determining the activity and selectivity of electrocatalytic reactions. Experimental techniques such as impedance spectroscopy and cyclic voltammetry measure the capacitance of the EDL, thereby providing a macroscopic view of how adsorbates or surface modifications influence the electrode-electrolyte interface. However, these measurements do not directly yield detailed microscopic information. As a result theoretical simulations have emerged as indispensable tools to gain deeper insights into the EDL at the atomic level, such as the specific arrangement of water molecules and adsorbates. At the same time, in many cases, experimentally observed double-layer capacitances are not reproduced by theoretical calculations, which puts a question mark behind their quantitative accuracy. This holds both for classical molecular dynamics (CMD) approaches based on force fields (FF) and ab initio molecular dynamics (AIMD) simulations based on Density-Functional Theory (DFT). While the former methods typically underestimate capacitance values (∼7 µF/cm 2 vs > 40µF/cm 2 in experiments) and oversimplify interfacial water structuring , AIMD simulations struggle to accurately model the electric double layer at realistically low ion concentrations. In previous works, we removed the challenge to model ion-specific, electrolyte response properties from DFT-AIMD simulations by introducing homogeneous, electrolyte counter charge distributions via partially charged hydrogen atoms and showed that the inferred capacitance vs potential curves reproduce experimental capacitances at Pt(111) at high ionic strength. These results suggest that an according analysis and comparison of FF-CMD and DFT-AIMD simulations might be able to resolve the central mechanisms behind the persistent failure of CMD to explain experimental capacitance magnitudes.