You're ignoring somebodys suffering by saying "just don't worry about it, nobody cares". Who are you to tell someone to not worry about what brings them suffering? What you're actually saying when you say that we can work on ourselves in mind body and spirit is that people who stutter are at fault for their stuttering. If they just work on themselves it'll be all be ok. But here's the thing. No amount of self reflection will alleviate stuttering because stuttering is neurological. This is a positive for us, this very fact that stuttering is neurological allows all the blame and stress we put on ourselves to be freed.