[drothlis]

I suspect it's because so many Emacs tutorials out there cover the same material as the built-in tutorial. And so many pre-packaged Emacs configuration files disable the menu-bar for no good reason other than that's what everyone else seems to be doing.

e.g. "Emacs Prelude", one such configuration or "distribution" of Emacs, used to disable the menu-bar by default as recently as a year ago: https://github.com/bbatsov/prelude/commit/878cffb