Why is this a horror story? Under certain assumptions of how the author intends to use this, this sounds like a sensible way to define a dynamic list of phony targets to me, without having to specify them by hand.
There are many reasonable scenarios why you might want to do this: determining at the point of calling make which targets to force or deactivate for safety, projects with nested or external makefiles not directly under your control, reuse of MAKECMDGOALS throughout the makefile (including propagation to submakefiles), ...
Now make bar and make foo bar will disagree on whether foo is phony, which may or may not be what one wants depending on both what foo and qux do, and how bar depends on foo and qux side effects.
It also very much depends on what the intent is, notably such a "autophony" make foo is very different from make -B foo.
There are many reasonable scenarios why you might want to do this: determining at the point of calling make which targets to force or deactivate for safety, projects with nested or external makefiles not directly under your control, reuse of MAKECMDGOALS throughout the makefile (including propagation to submakefiles), ...