I understand that there is finagle and also a service discovery backed by zookeeper. I fail to understand how twitter's data stays consistent without something

I understand that there is finagle and also a service discovery backed by zookeeper. I fail to understand how twitter's data stays consistent without something like linkedin's databus. Doesn't twitter manage a single point of thruth or a single version of thruth and propagate changes to secondary databases like social graph & search indexes?