Autobiography as De-facement

Paul De Man's piece is an interesting text based on the fact that he takes the time to extravagantly point out several of the problems that I have noticed over the past few months. I'm not saying that I agree with his observations, as I tend to mostly disagree his arguments. Since it's publishing in 1979 I figure that things have changed a bit over the years but to put things into context for modern times, and as we have seen over and over again the definition of autobiography is as such:

[f. AUTO-¹ + BIOGRAPHY n. Neither this nor any of its derivatives are in Todd 1818; only Autobiography in Craig 1847.] The writing of one's own history; the story of one's life written by himself.

We may have to take this "writing" in the most literal sense to mean a novel or book form, seeing as how de Man has applied blinders to the ideals of applying the autobiographic process to all types of medium. That aside, he states blatantly that the form of autobiography does not fit into any category , genre or mode, but merely a contract or sharing of knowledge that what is written is, in fact, a true story about one's history.
De Man rejects the idea of autobiography as a genre, in somewhat of a ridiculous notion to me, due to the idea that we could mistake all stories told as true stories. This only being caused by the fact that authors of autobiographies would abuse the use of figurative language and produce something that parallels a fake story, thereby, later in time, blurring the borders between fiction and non.
Looking to the reverse though, does not something that can be as obscure as fiction also be reduced to the idea of requiring a contract of mutual understanding that the text is not real... "so don't go out and try to jump off a building because you think you can fly."

To close I'd like to look briefly at the paragraph on pg. 922 which cites Genette and the idea that an interest in autobiography demonstrates the impossibility of allowing textual systems made up of tropological, metaphorical, substitutions to come into being. Well, to me this brings to mind an idea of a senile person writing an autobiography; within their dreams, which they tend to write about, everything appears as a metaphor. Do we have to take what is written as the truth. Maybe I've missed my point... why must autobiography stray from or deny the existence of metaphor? Can we as a culture not embrace the idea that not every word is truth and as an autobiography, written by man, must in some way always be wrong. It is only human to err...
I think I missed it again.