When a bass bites a jig it usually inhales the entire bait in one quick move and, the bait will usually be well into the mouth of the fish by the time the hook is set. Most pitching rods are stiff and have little play in the tip so there is little room for force to be absorbed in the rod. The amount of line involved in pitching is usually short. The shorter the line distance between the rod and the fish the lower amount of force that will be absorbed by line stretch. Fish size is another important factor.
Big fish absorb less shock then small fish.
Small fish will move or turn in the water when the hook is set. Bigger fish however do not move as much on the initial hook set due to their heavier weight in the water. If, when the hook is set in a big fish, the line, the rod or the fish do not give much then there is only one other thing that can - the flesh and bone of the fish. I used to set the hook about as hard as I could. I noticed however that I lost a number of fish on a jig even when the jig was deep in the mouth of the bass.