For me, stuttering has absolutely nothing to do with social anxiety. If there are certain words that are hard for me to say, I will stutter when trying to say those words even when speaking to myself. Social anxiety can certainly make stuttering worse, but it is not the root cause of real stuttering (normies don't understand what real stuttering is). I have reached the age where I no longer care about what other people think, so I don't have social anxiety anymore, but it hasn't removed my stuttering completely. However, I now stutter about the same in public as I do when speaking to myself, which I see as progress.