I doubt very much indeed whether any rear seat aircrew except navigators and air engineers would be capable of necessary task skills.
Sorry, Mate, you are wrong. Although your implied point on apptitude is accepted: as a serving scroat, non Nav, non FE, I am quite capable of getting get a fix; be it radar, beacon, transferred position line or pinpoint, et al; and then windfind, fixed depart, intercept/reintercept a moving waypoint using a Dalton, (inside of 4 minutes).
So I can't do MSO?
Thanks for the bigotry.