It may not stop the first time but you aren't relying on the collar to stop the behavior, you are relying on the collar to help you remind the dog that you are there.
Example: You are socializing your German Shepherd who is 8mo old. You are taking him for a walk through an area that will have distractions because at this point in his training you trust he is ready for this. While on the walk you go past a yard with a dog on a chain and when it sees your dog it starts barking and pulling towards you and your shepherd.
This excites your dog and he begins to bark and pull and lunge in the direction of the chained dog. He doesnt respond to verbal commands, is fixated on the other dog and is getting to an excitement level that is not acceptable anywhere, especially in public. This needs correction because just trying to walk away from this does not teach the dog that this isn't acceptable and it can lead to dangerous situations down the road.
Here is where you're glad to have that tool. You shorten the leash if you have not already, snap your wrist like you're flicking water out of a paint brush and the pinch/choke acts as a distraction to remind the dog that you are there. You use it to reinforce your verbal command and clear the fog of excitement. Now you can show your dog the correct behavior and rinse & repeat. You didn't play tug of war with a dog that is getting stronger each day and you didn't allow the behavior to continue. You safely used a training tool to correct a problem behavior that could have serious medical and legal repercussions down the road