Stuttering is considered a disability. There are certain people who have such a sever stutter that it incapacitates them from communicating at all, which is necessary in most societies. Also, since you seem to be uneducated on the matter, a stutter is both neurological and psychological...the neurological part cant be changed. A person can hide their stutter well or adapt techniques that make it seem the they dont stutter to the untrained but usually people who stutter past the after of 12 will stutter for the rest of their lives. Theres nothing wrong with catering a device to people who need it, specially if that percentage of people are in the millions.