It should be noted that the article is written to sell services for Terraform. It is unfortunately built on a few false premises that are never argued. Very few Chef developers would agree with Chef being somehow more imperative than Puppet, for example, seeing how the language was originally thought of as a superset of Puppet's.
The author does not specify which module is used for AWS, but it is not representative for how one would want to use Ansible for infrastructure. Writing idempotent playbooks is widely regarded as best practice in the Ansible community.
I have used Ansible for declaring node state in large production environments (not some dinky startup) and found it to be a very straightforward way to manage infrastructure.
[1] https://blog.gruntwork.io/why-we-use-terraform-and-not-chef-...