The PL Zoo is a great resource, but that's not exactly what the blog post is advocating for. PL Zoo is meant for students studying the implementation and design of programming languages.
What the blog author is describing, on the other hand, is a small language for teaching the use and application of certain programming techniques.
It's a very promising idea, one that I may try to bring to life for something tricky, like monads or maybe Rust's ownership system.