That's the craziest assertion that you have ever made! Least consistant GUI?
Absolutely. Most apps use their own icons. You don't know if it's CTRL or ALT-[key]. No consistency in the preferences dialogs/controls. Then shortcomings regarding user input widgets. No consistent help system. Often bad or incongruent keyboard control. All that should IMHO be established/determined by the OS, not the application.
The app developers need something to write for, period. R1 is that base that
they need.
Well, as R1==R5, they can pretty much use R5, not so?