No, you don't need them, ChasFidjit, within the terms of this thread, which started off with a simple request as to how to do the simple 3-chord trick accompnmnt; which I & others endeavoured to answer simply. Now the thread is being hijacked, as I perceive it, by a whole lot of those who want to show what clever effects they can get by complex rather than simple progressions. They should start a new thread, called 'The augmented/diminished/modulate·till·blue·in·the·face chord tricks' or some such, & leave this one to the ones who started it off, wanting to know how to keep it simple but effective.