I do not understand why the GFDL exists at all. It seems to me
that the
GPL is as adequate for manuals as it is for code.
The GPL was designed for software, not for books. The GPL's
requirements would be quite inconvenient for anyone who wanted to
publish a printed book from the material.
I think the GFDL says more or less what it ought to say.
OK, for books it makes sense. But it doesn't for material such as the elisp
manual (which is not published).
Stefan