Why not use Service Integration?

[robertbio]

Is there any reason why one should not use the direct AWS service integration from API Gateway to DynamoDB?

Some say that the best lambda function is one that does not exist. I see that the two connecting lambda functions could be avoided in your design and I wonder if there is any good reason to keep them.

Using something like this: https://aws.amazon.com/blogs/compute/using-amazon-api-gateway-as-a-proxy-for-dynamodb/

Only one thought comes to my mind, the db throttling retries implemented in the SDK.