Your argument is the equivalent of, “I saw someone get stabbed to death so you shouldnt wear your motorcycle helmet.”

I have no doubt you did see these things but that doesnt mean loud pipes dont add a bit of safety at the expense of noise comfort. Every bit of safety adds up and can save your life. There is no one thing that will do it but if you do enough it can have an effect. Maybe you didnt hear those pipes but a few hours later someone else did and didnt see them and they were saved.