Comment by jolynch
(post author)
It is indeed similar to DynamoDB as well as the original Cassandra Thrift API! This is intentional since those are both targeted backends and we need to be able to migrate customers between Cassandra Thrift, Cassandra CQL and DynamoDB. One of the most important things we use this abstraction for is seamless migration [1] as use cases and offerings evolve. Rather than think of KeyValue as the only database you ever need, think of it like your language's Map interface, and depending on the problem you are solving you need different implementations of that interface (different backing databases).
Graphs are indeed a challenge (and Relational is completely out of scope), but the high-scale Netflix graph abstraction is actually built atop KV just like a Graph library might be built on top of a language's built in Map type.