Is it common to not throw hard jabs when fighting?

How do you know it doesnt hurt them thats not possible the jab is a punch to keep your opponent away, to fight on the outside its not technically a knockout punch its just for points but its the most important punch in your arsenal dont make it as a hard shot like your cross make it fast and snap. Dont act as if your going to break your opponents jaw act as if your trying to steal his mouthpiece you might think it doesnt hurt but it does and can really annoy your opponent and set up power punches