The idea is that your container image is the thing you want, and is (relatively) immutable, so you delete and create containers when you want things to change. If you need state you can do that with volume mounts, but the idea is that you don't need to 'update' a container, you just replace it with a new one.

That's also what docker compose does, under the hood. It doesn't 'update' a container, it just deletes it and recreates it with the new image and the same settings/name/ports/volumes/etc.