Exercise left for the student
Roy Fielding: Getting two components to communicate is a trivial process that can be accomplished using any number of toolkits (including the libwww ones).
It is fun seeing one of the primary authors of the HTTP spec lecture one of the original designers of a key portion of what is the dominant web browser on the Internet as to what exactly is and what exactly is not trivial.
Unsurprisingly, Roy gets a cool reception. I guess when the oracle has spoken, I'll just accept the dictum and move on. Indeed.
Meanwhile, today I saw a demonstration of some new Adobe tools that will allow GUIs to be generated from a schema, complete with validation code. The target audience for such tools is clearly different than Roy's. In particular, libwww is far beyond their abilities.
None of this invalidates REST. It merely recognizes that there are a number of non-trivial problems in getting two components to communicate, and that REST addresses in an admirable fashion one significant portion of the problem for a significant use case.