+1

If the article had used I/O (http request) as an example of event handling (message queuing), it would have added some concurrency context.

setTimeout uses the same message queuing system as XHR, DOM events, or communicating with stuff that has its own stack like iframes or workers. That's why a function with a timeout of 0 will not fire until after it's enclosing function has popped. Functions block. Waiting for messages doesn't. That's the model for JS concurrency.

I agree.