R.A.N is just a fancy way of saying you need to have multiple representations of “root” intent based on the various parameter permutations (missing/present parameters). This is really nothing new here as far as I can tell..
Webviews have their place, especially if the parameters that need to be entered are large and have inter dependencies and validation logic..etc.
I do agree that balancing the use of decision tree vs webview flows is an important consideration in any CUI.
There are a number of ways to perform intent slot filling and intent chaining that is really at the heart of what I think this article is trying to tackle with how to build a complex conversational dialog.
Maybe I am missing something but I am not seeing anything substantive here.