I think the real advantage boils down to two things that really only matter in campaign play, and real life:
If one of the two is badly damaged, the damaged one can attempt to disengage while being covered by the less damaged craft, this providing at least an opportunity for one or both of the fighters to live and fight another day.
If their craft is disabled or shot down, having a wingman means that if possible, your side should have a good idea of where to go to save the pilot(s)
Getting higher survival rates for your crew who are in damaged or destroyed figures is critical to reaching veteran and elite status (not to mention the cost savings if you can recover and repair the fighters)