You can't dodge bullets. That's why they were invented.
You need much more agility and strength to kill someone using a knife than a gun. Implying that you are not trying to shoot someone running in zigzags in a field full of covers from 300 meters range with a handgun, accomplishing this will be kinda hard.
If you compare stabbing someone in the back to shooting someone who shoots you back, well, you are kinda stupid then. Because if you can approach someone from the back to stab him you can shoot this person in the back of the head from point blank range too.
Again, i gate when people talk about knife fights and all i hear is "stab", main purpose of knife in a fight is to slice you opponent, you slice his arms, eyes, face, w.e. is not covered with clothes so he won't be able to fight you back and probably will die from loss of blood/infection if he will not get medical assistance. It requires much more effort, strength, experience and agility than aiming and pulling a trigger.