Why is SubscribeToShard not available for the AWS SDK for .NET?

I'm working with clients who are locked in to using the AWS SDK for .NET. They are reading records from a Kinesis stream, and I suggested they use SubscribeToShard method because it worked so well in the SDK for Python. But it didn't seem to work in .NET and the above documentation page gives a 404 page. Furthermore, the API documentation for AmazonKinesisClient does not list the method, even though it is referenced in the RegisterStreamConsumer method which seems to be available.

Is there any reason why this particular method is not available in the SDK for .NET?