Worth noting his original reason for moving away from DynamoDB is outdated. DynamoDB added an “adaptive capacity” feature to handle hot partitions.[1]
[1] https://aws.amazon.com/blogs/database/how-amazon-dynamodb-ad...
[1] https://aws.amazon.com/blogs/database/how-amazon-dynamodb-ad...
Definitely adaptive capacity targets the primary reason people had to overprovision DynamoDB. It changes the entire calculation and obsoletes all the advice you might have heard based on experiences prior to late 2017.