I'm not sure that's true of all the client libraries - I'm pretty sure that the Java library is used heavily internally within Amazon to leverage AWS services. Just look at the release history: https://github.com/aws/aws-sdk-java/releases

But you're right, maintaining even a blessed third-party library like boto is a massive undertaking: 437 contributors, 431 open issues, 192 open PRs. Competing against CloudFormation using anything other than the Java client library is crazy IMO.