You shouldn't make such assumptions. There are definitely people who have overcome their stuttering. You are correct if you mean 'there is no standardized cure that you can go to a doctor or a therapist to get a treatment for' ....but not in the sense that "a cure does not exist"...it's possible you have not run across the cure yet or that it is complicated and takes a lot of effort. my background is that I had a health issues that "had no cure or treatment " that is now almost completely gone from my self effort and also getting really lucky