I'm not sure if the attack surface is effectively reduced with the use of cointainers. Of course, the user is now in his own namespace, but in order to achieve

I'm not sure if the attack surface is effectively reduced with the use of cointainers. Of course, the user is now in his own namespace, but in order to achieve this, an additional file system, another network interface and a container runtime have been added, thus effectively doubling the complexity. Containers are great if you want to present a service to the outside world or if you want to set up a clean workspace locally. But I wouldn't be comfortable with the thought of letting someone I don't trust into the server behind the firewall. Depending on the configuration, you can reach other local containers via localhost:${port}. An with overlayfs there was afaik a case where you could actually access restricted areas of the underlying filesystem.