Honestman, I agree that a single approach to waffle wouldn't be as useful when it comes to multi-author pages like forums and comment sections. They're greater than the sum of their words, and they do tend to invite duplication.
However I don't think this is an insurmountable difficulty for the engines. They're at least quite good at figuring out whether the page is a forum or a blog, so in theory an algorithm could split the contributions up by author. A long, boring comment shouldn't detract (too much) from an excellent, concise blog post and there should be some way to recognise that. Yet there's also a need to cut through the noise on busy comment systems: either with editorial comment highlighting like the BBC does, or a user moderation system.
So, I guess the presentation training that extolls "Tell them what you're going to tell them, tell them, tell them what you told them" is right out the window.
I don't know. For a certain audience that's going to be useless filler, but for others it's desirable. But there are lots of different types of waffle. I'd be more concerned about repetition of phrases/ideas within the same paragraph, using three adjectives where one would do, and the overuse of empty words: sometimes you can point to words that everyone agrees are better off struck out.