No one's actually said that to me, but I do get treated like I'm stupid/slow a lot (yes, I know that autism /= slow necessarily, just saying). I honestly think that, quite to the contrary, even though I don't speak much stuttering has made me better at understanding interpersonal relationships and maybe more emotionally/socially mature because I'm constantly observing other people interacting, always planning conversations in my head, anticipating what people will say/think.