I never understood that argument. What prevents emacs-devs from maintaining an emacs-core with all modes outsourced to ELPA, and still deliver a emacs-classic-d

I never understood that argument. What prevents emacs-devs from maintaining an emacs-core with all modes outsourced to ELPA, and still deliver a emacs-classic-distribution which loads packages from elpa on compiling? You can easily mark versions of the elpa-packges matching the emacs-classic-version, while developing it independant from it.