I don't think this article is very good. The main achievement of message passing is to decouple call stacks, and the reason why you do that is that you get more

I don't think this article is very good. The main achievement of message passing is to decouple call stacks, and the reason why you do that is that you get more control about which threads a function is called from. You turn to message passing because you want to get away from callback spaghetti. The article doesn't even mention concurrency.