That's somewhat inaccurate. The stapedius muscle as part of the auditory reflex (above 85 dB) contracts and protects the cochlea from transmission of high intensity sound--but its function is variable across the population and it's uncertain if it actually prevents hearing damage. I'm guessing it mitigates it...
Even if that is the case damage still occurs, I am not disputing it mitigates it as I am no doctor, but even when wearing ear plugs you can still cause damage to your ears as they are only rated up to a certain DB level. Point is that whether you notice it or not, shooting a gun without protection will damage your ears every single time no matter how miniscule the damage is.