What kind of automation you wouldn't do with Ansible and why?

While it's possible to provision resources with Ansible, some prefer to use tools that follow immutable infrastructure paradigm. Ansible doesn't saves state by default. So a task that creates 5 instances for example, when executed again will create additional 5 instances (unless additional check is implemented or explicit names are provided) while other tools might check if 5 instances exist. If only 4 exist (by checking the state file for example), one additional instance will be created to reach the end goal of 5 instances.