Configuration management tools have as their primary objective the task of making a server always be in the desired state. If a web server stops, it will be started again. If a configuration file changed, it will be restored. No matter what happens to a server, its desired state will be restored. Except, when there is no fix to the issue. If a hard disk fails, there's nothing configuration management can do.
The problem with configuration management tools is that they were designed to work with physical, not virtual servers. Why would we fix a faulty virtual server when we can create a new one in a matter of seconds. Terraform understands how cloud computing works better than anyone and embraces the idea that our servers are not pets anymore. The are cattle. It'll make sure that all your resources are available. When something is wrong on a server, it will not try to fix it. Instead, it will destroy it and create a new one based on the image we choose.