Albie,
That's your point of view. However, from the captains viewpoint, it takes at least 2 and sometimes 3 really good f/o's to do the work of the captain. This proves out on long Mad Dog trips, with at least 2 f/o's and only 1 captain.
It takes, one good flight engineer to replace another, because the guys in the front know absolutely nothing about what goes on behind them. But of course, the guys up front could care less.