Ouch. If you prick me, do I not bleed?
My point is, it's not as if the FA Cup itself uniquely "retains the magic". Football as a whole has that magic, it's just you don't get it every day.
Just yesterday we had an even more magic moment in the Watford - Leicester promotion match but I don't hear any cries that we should prioritise playing in the Championship because that's where the magic is retained.
The variation of results is one of the sport's chief attractions and always will be.