> This led to Facebook designing React to let devs write encapsulated components with predictable output and behavior, but React didn't have a solution for larger global state. Facebook later announced a "Flux Architecture" concept that tried to make larger app state updates predictable through centralization.

Can someone explain this to me please? How is it possible, that Facebook, did not have a plan from the beginning for a larger global state, even though their own app is huge? How did they solve it in Facebook in the first place? or did they started using React for themselves AFTER solving the global state problem somehow?