I am not too sure about that, but having operated for 6 yrs as an FE then progressed thru the other two seats, The FE's job is more than worth his salary in maintenance cost reduction, and enhanced safety when there is a tech problem in flight.
Most F/O's have little interest in the technicals of an aircraft except for what they have to know, their prime objective is the seniority list and how soon can they get a command!
Admittedly I fall into a minority category where I did 4 years as a ATC at a then International airport before moving along to the F/E seat and so on.
But a couple of years min.
in the third seat sure brings one up to speed in technical knowledge of the equipment one is operating.
The few extra switches comment, is raw untreated sewage.
BBG.