I hear you, it would definitely be better if there was a guide in the docs for Phoenix.PubSub or for Phoenix itself.
Without that we’re relying on material from elsewhere in the community. And, while there’s plenty of good material out there, it’s not easy for someone getting started to know where to look, and nothing beats “official guidance.”
With documentation there’s got to be a balance between assuming knowledge of the development model vs explaining everything to the nth degree. We probably don’t want the module docs for everything that sends messages to start with explaining message passing in the BEAM, instead guides are a much better place to explain those underlying concepts.
Every framework and language has different implications of what it means to the a “web developer.” What do React’s useEffect or Rails’s “Controller” have to do with HTML, CSS, and the DOM? Those are concepts that are used for web development in those ecosystems, and how to use them effectively is something that’s learned with experience.