As per DynamoDB's documentation, it supports both key-value and document-oriented properties of NoSQL even though other NoSQL databases fall only under only one type either Key-Value, Document Graph, or Column-oriented.
Also, it says:
Amazon DynamoDB is "built on the principles of Dynamo" and is a hosted service within the AWS infrastructure. However, while Dynamo is based on leaderless replication, DynamoDB uses single-leader replication.
And Dynamo is:
A set of techniques that together can form a highly available key-value structured storage system or a distributed data store
So when DynamoDB is built on the principles of Dynamo which is not related to a Document-oriented storage system and since it is mandatory for a developer to create a primary key and the table requires a key for every item how and in what sense DynamoDB is called a Document-oriented database?
Can a DB fall under two types of NoSQL databases in the first place?