Like many things in technology, the architectural arguments repeat themselves. Almost as soon as containers became hot, users were clamoring for better container security, networking, and management tools – as also happened when other areas of technology such as client/server and the Internet arrived on the scene.
The container ecosystem has moved to building out the features necessary to manage, secure, and network the container infrastructure. This includes tools specifically targeted at Docker networking, security, and management. Going back to the client/server paradigm described with Docker, think of how a container system functions by using client interfaces to communicate with daemons installed on top of a Linux OS on data center compute nodes.
Both Docker and LXC applications use APIs and networking resources to communicate. In addition to the compute resources on the node on which it is installed, the containerized application still needs access to resources such as storage and networking. You also need to be able to manage and control the orchestration of containerized applications, as well as secure them.