If we could already do it with some loadbalancer changes, I don't understand your comment that it was an incentive to move to containers.
Containers are separate from their deployment method. To be able to do those things with containers, some will go to docker, docker swarm, hashicorp nomad, or kubernetes.
So if people could already do these deployment methods, and given the HUGE organizational lift in training and platform investment for Ops to do that shift, your comment about those reasons being incentives to move to containers doesn't make sense.
I think virtually nobody cares about being able to change the image of a container when you can so easily start a new one.