Hmmm. I appreciate the way you laid out your argument, I'm not sure I understand it entirely though. I agree that the concept of authorship is not very logical in the context of your example, but I don't know of any HTML spec which requires defining an author for each document? I think my point was that it's pretty easy to mark up data in a semantic-enough way using the current tools. A wall post doesn't need to be a document of its own, it can be an item in a list of wall posts that make up part of a bigger page. I agree that "document" is sort of a silly metaphor for that use case, but that doesn't make HTML any less useful. We could use XML, but that would basically be the same thing. We could use JSON, but again... it's just another way of drawing the same relationships. I suspect that I've completely missed your point though, in which case I apologize and please be patient with me!

With regard to the rest of your comment (7 unrelated technologies, deep layers of markup, huge numbers of LOC, etc) I agree, but as you said - how could it be fixed? The reality is that the web performs a complicated function. It would be nice to abstract the nuts and bolts behind it away cleanly, and I don't think it's unreasonable to believe that could happen in our lifetime, but it's also not unreasonable to expect that developing for a complicated platform will be complicated.