Containers are not a security barrier. They cannot be, they never will be.
Not entirely true. If you're hosting multiple game servers on one machine, for example, it's best to run each instance in a container. Game servers, by their nature, are required to have public IPs and ports, and some of them run on old engines that are vulnerable to various DoS methods. If your server is attacked, it might crash the container(s), but it can't bring the whole server down.