Ansible will not clean up after itself when you revert a diff. Once added, you can't remove a resource from the desired state unless the tool has a way to remember resources it created so that it can decommission them.
It's funny you mention this. Removing resources from AWS is the one thing that reliably breaks in Terraform all the time.
If you have never tried to destroy all your Terraform resources before, it will probably not work. You'll have to modify your Terraform to get it to jump through the correct hoops in the correct order in order to destroy without dying.
At this very moment I am fighting with Terraform to destroy some resources as part of a code change. AWS wants them destroyed in a very particular way, and Terraform won't create the resources I do want because apply is dying because the destroy is failing.
That's a good point, but sadly not how tools like terraform marketing themselves. If terraform markets itself as "we make clean up easier for that 10% of time when you need it, and to achieve that goal, we give you 3 times more headache by asking you to keep states", I am sure many more people wouldn't make the trade-off.
