> > Wrt the advantages and uses of dynamic binding in the
> > context of _Emacs_ - i.e., the reason why Emacs has, and
> > should continue to have, dynamic binding (along with
> > lexical binding), see RMS's arguments here:
> >
> > https://www.gnu.org/software/emacs/emacs-paper.html#SEC17
> > https://www.gnu.org/software/emacs/emacs-paper.html#SEC18
> 
> If that's the "options" argument I don't see what's so
> dynamic/special about that idea, to me they are global
> variables rather like any global variable found in any
> programming language ...

You might want to read it again.  It's not
complicated.  And it's not trivial.

You might also want to check out "Common Lisp
The Language".  Unlike the CL "hyperspec", it
presents (also) the design of the language
and the logic behind it.

RMS's arguments are specifically for users
of an editing environment such as Emacs.
They go beyond the general arguments for
providing dynamic binding (in addition to
lexical) in Lisp.