This is not totally true. There are ways to ensure a read from a follower sees the latest writes from the same client. You do this by sending the index of a client's write back to the client upon success and the client sends that index to a follower when reading. The follower awaits logs up to that index before servicing the read. Some Raft implementations do this, but clearly it can cause greater latency when switching between writes and reads and still only gets you sequential consistency and not linearizability.