The author can function well as an identity for intellectual
rights, or even, as in the old days, for someone to blame for writing a 
particularly blasphemous text. Any function outside of these areas serve 
little meaningful purpose.

   We can see that while Harris's intellectual rights are protected he quotes
from, among others, Dante. Yet it is not mentioned in the start that 
Harris's rights do not apply to the translation of part of Inferno.

   How about 'Carole Baron, my publisher, editor and friend, helped me
make this a better book'? Is there a threshold where another person can 
'help' to make a book better but still fall short of being an author?

   And what of the characters that Harris maintains only have a coincidental
resemblance to any living person?
I am quite sure the ideal in popular fiction is to create as real characters 
as possible. The background characters that are mentioned in the book no doubt
would have a resemblance to quite a few people. eg how much of Stephen
Hawking belongs to Harris's creation and how much to the media that made 
Stephen Hawking, the man that he was?

   An author does not write only a particular genre or in a particular area
only. An author continues to live after writing a text. In any point of his 
life, should he change his decision, is he a different man from the one that 
writes the previous text?

   He still goes by the same name does the same things eat the same food. He 
only changed his mind on a topic.
The author as a function fails to unite the two authors separated 
temporally.
Then again if the text's author changes his mind does the text change its 
meaning?

NO!
Do we need the author then if the text is the desired object?

 Online Collaboration  Remains of the Day  Quoting An Author   End Credits