"Environment variables is exactly this: mutable global state." No it isn't. Every time you start a process, it gets a set of environment variables of its own, which won't be changed by any further changes in the parent process. This is the opposite of how global variables work and is exactly how function arguments work.

The rest of the article isn't very good either. The examples of running a program with two different states and of trying to do nested escaping would both apply to any means of passing configuration.

I also find it hilarious that the author suggests using JSON configuration files instead, which actually have many of the problems that this article falsely claims that environment variables have.