> I'm not sure who started this whole container is just a process thing, but it's not a good analogy. Quite a lot of things you spin up containers for have multiple processes (databases, web servers, etc).
It came from how Docker works, when you start a new container it runs a single process in the container, as defined in the Dockerfile.
It's a simplification of what containers are capable of and how they do what they do, but that simplification is how it got popular.
Not just the kernel and PID 1, we also tend to refer to the rest of the system as "linux" as well, even though it's not technically correct. It's very close to the same simplification.
It came from how Docker works, when you start a new container it runs a single process in the container, as defined in the Dockerfile.
It's a simplification of what containers are capable of and how they do what they do, but that simplification is how it got popular.