Not quite true, you can technically create your own CloudFormation resources[0]. It's a pain to do though.
[0] https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGui...
[0] https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGui...
[0] https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGui...