Maybe in outdated medical literature (stutterers are only 1% of the population, so it won't be a widely researched topic) and/or there's no UNIVERSAL cure (but many people still recovered somehow). Stuttering has no organic causes most of the time, and the brain can rewire its corrupt neural pathways, so it's nonsense to assume there's no cure. People recovered from much worse conditions, can live with half of their brain missing, BUT stuttering is incurable?