A container can also give your application assurance that the file system looks a certain way. But you are right that you can get pretty far with bundling depen

A container can also give your application assurance that the file system looks a certain way. But you are right that you can get pretty far with bundling dependencies and assets and configuring all nontrivial paths with environment variables. However, the choice of containers for Kubernetes is a pretty fundamental one. It simplifies distribution of deployables to a single workflow also for programming languages that don't offer monolithic deployables, to legacy application not originally intended for Kubernetes, or that don't follow the 12 factor app principles.