Modern password hashing remains a critical defense against credential cracking, yet the transition from theoretically secure algorithms to robust real-world implementations remains fraught with challenges. This paper presents a dual analysis of Argon2, the Password Hashing Competition winner, combining attack simulations quantifying how parameter configurations impact guessing costs under realistic budgets, with the first large-scale empirical study of Argon2 adoption across public GitHub software repositories. Our economic model, validated against cryptocurrency mining benchmarks, demonstrates that OWASP's recommended 46 MiB configuration reduces compromise rates by 42.5% compared to SHA-256 at \1/accountattackbudgetsforstronguserpasswords.However,memory−hardnessexhibitsdiminishingreturnsasincreasingallocationstoRFC9106′s2048MiBprovidesjust23.31) and 17.7% (\20)additionalprotectiondespite44.5timesgreatermemorydemands.Crucially,bothconfigurationsfailtomitigaterisksfromweakpasswords,with96.9−99.8