Why Syncing Props Into React State Creates More Problems Than It Solves

A React development guide highlights a common but problematic pattern where developers copy prop values into local state and use useEffect to keep them synchronized. The core issue is that React already re-renders a component whenever its props change, making the duplication unnecessary and creating two independent sources of truth for the same data. While the pattern appears to work correctly in simple cases, it becomes error-prone as components grow to include features like polling, optimistic updates, or live WebSocket data. When new server data arrives while a user is actively editing a field, the Effect may overwrite user input, creating ambiguous and hard-to-debug behavior. The guidance recommends deriving values directly from props rather than duplicating them in state, eliminating the need for the synchronizing Effect altogether.