You can be right on the numbers and still lose the system. This paper explains a failure pattern that keeps repeating in policy, institutions, and high-stakes decision systems: interventions that are technically correct, evidence-based, and even “compliant” can still collapse because legitimacy breaks first. Within Zero Leap Theory (ZLT), legitimacy is formalized as the alignment gate (Φ)—a non-compensable, pre-intervention condition. When Φ drops below Φ_crit, resistance becomes nonlinear: compliance can turn into sabotage, coordination collapses, and the intervention’s net effect flips sign even if the underlying technical model is correct. The paper introduces IAS-LEG, an auditable protocol to detect legitimacy risk before action, and integrates the Exit Coercion Index (ECI) to separate real consent from coerced compliance. A core warning follows: apparent success under high coercion is often a delayed failure, not validation. This is not a moral lecture. It is a structural claim: legitimacy functions like a constraint in systems with memory. If you ignore it, your intervention may “work” short-term while irreversibly degrading the system that must carry it.