In the 1980s with the B747s and DC-10s, Wardair had PFEs. This made sense as they used to fly to places where they did not have a lot of staff, so it was handy carrying an AME rated on the aircraft type.
With the order of the A310s, the "writing was on the wall" so when the A300Bs were leased, they did not have the PFEs, but actual pilots hired into the FE
position, with the intent of moving to F/O when the FE
position was eliminated. They were referred to internally as "FE2s".
With the sale of the DC-10s and the eventual replacement of the A300Bs with A310s, the FE2s moved into F/O positions, but the PFEs were left hanging. In deference to the time they put into the airline, they were offered the opportunity to move to the F/O position if they were able to achieve the licencing and experience. To their credit ... 9 made it! While most have retired, there are still a few around today flying as B767 and A320 Captains!
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!