the trouble is that HTML is anything but generic. If you've ever tried to write a web scraper that can be used on _any_ webapage you quickly discover that its near impossible. I use to belived that there should be one way to use HTML to describe the page content and the rest should be CSS but gave up as its completely inflexable and the approch has been abandoned for simply describing presentation as this is actually practical. You'd need a HTML structural standard, but that will get mostly ignore (as have most of the W3Cs recommendations on that subject).
As you said "REST" and "RESTful API" are different beast, i guess the "-ful" should be more of an "-ish".