Yes that's true. Also interesting is, AFAIK, DynamoDB does not follow the Dynamo paper. DynamoDB uses an architecture based on single-leader replication, and the Dynamo paper describes a process where a coordinator node is in charge of replicating to each node. If I am not confused, any node among the top N nodes in the preference list can act as the coordinator.

(This information may be slightly out of date at this point)