Ain't that the truth! I'm wading through Lambrecht's Information Structure and Sentence Form: Topic, Focus, and the Mental Representations of Discourse Referents right now. Talk about dense! And confusing doesn't begin to describe it...I've heard people say it is one the hardest books they ever read. I agree. I'm not sure if it is the subject or the writing—or both!
So, for someone to say that the whole idea of topic is "problematic" is refreshing. At least I'm not the only one confused...