The civil examination system (Keju) created a meritocratic bureaucracy in imperial China. Utilizing hand-collected career-path data of 5,353 bureaucrats over 1,400 years (265-1644 CE) and a difference-in-differences strategy, this paper reveals a hidden flaw in the system: while it increasingly recruited commoner-born elites into the bureaucracy, exam-era social elites became more vulnerable to extralegal political purges and featured shorter lifespans. When Keju erased the power checks from nobility, it cultivated and strengthened an absolutist rule where no social elites were safe. We thus highlight the necessity of institutional commitment arising from checks and balances in fostering pro-development social environments.