Basically, configuration management is thinking about the problem backwards. Taking a mutable filesystem and trying to flip things until its in the desired stat

Basically, configuration management is thinking about the problem backwards. Taking a mutable filesystem and trying to flip things until its in the desired state is complicated and prone to a lot of problems, I used SaltStack for 4 years in production, it's hard to enumerate the number of ways that didn't work well. Building an image from the ground up is the other direction. The difference is subtle, but if you have an exact known starting point, then declarative configuration management is not only unnecessary, it's downright worse than just running a few commands to get to the desired state. The proof for me is in the pudding. Container building is a superset of configuration management. You can definitely use Ansible or what have you to build a container root image, but it would be long, overcomplicated, and more fragile than just starting from a known state and mutating from there.