In this game you can probably get away with it if you are carrying AIM-9Ls at a minimum and are not going against a fighter with missiles, or something like a MiG-17F (if on post 2008 patch).
If a missile is fired at you or you are going to merge those stores have to be jettisoned - otherwise its suicide, and in RL you can damage/write off the jet by pulling panicked extreme manoeuvres in the heat of battle - another reason to ditch stores.
The only way I could see this happen in RL is if the Jet with A-G stores is carrying something like an AIM-120 with standoff capability. Even then in a BVR contest you are at a massive disadvantage against another fighter with similar missiles due to it being largely an energy contest.
The AI enemy can give a false impression - fly against a competent human pilot in the same jet online in the 1970s and you will start to see why you need every advantage to survive.