DynamoDB to RDS using DynamoDB Streams and Kinesis(?)

I have a DynamoDB table that changes quite frequently (INSERTs, UPDATEs and DELETEs).

I want to reflect those changes into an RDS table.

I saw that some articles that suggest the following architecture:

  DynamoDB -> DynamoDB Stream Processor lambda -> (Kinesis Firehose <-> Transform Lambda) 
  -> S3 (transformed and untrasformed buckets) -> Lambda -> Postgres RDS.

It made me wonder:

1. Why do I need the Kinesis adapter in the middle?
2. Can I get a good-enough solution (1,000~ changes per second, or if possible even 10,000 changes per second) with another architecture, perhaps simpler one?