Why would a client/server query protocol replace the need to manage client-side state? No matter how you build your client/server syncing there is inevitably go

Why would a client/server query protocol replace the need to manage client-side state? No matter how you build your client/server syncing there is inevitably going to be client-side state that needs to be managed. You can't just assume that any action will be atomically and instantly synced to the server when you are operating over an (unreliable) network.