Not necessarily. Imagine something like this. Let's say you can walk without falling down if you're not wearing a backpack. But if you have to carry a ten kilogram backpack or a bag suddenly you realise that it's too heavy and you have to either stop walking or drop the bag. A ten kilogram bag is like a hundred kilogram bag for a regular person because you were born with a medical condition like a muscle atrophy. I mean it's not ideal but at least you can walk short distances under ideal circumstances. And maybe some doctors call you lucky because they know had your condition been any worse you couldn't walk at all. Now change muscle atrophy with a stutter. You can talk under ideal circumstances seemingly normally but if given seemingly small obstacle some neurological conditions makes talking hardly possible. A friendly stranger asking for a time overwhelms your brain area responsible for speech like being dropped into nuclear war zone with zero chance of survival overwhelms the regular person. Not all the brain areas, just the ones responsible for speech. You can still see hear, stand, smell normally. But chances of talking for a duration of interaction are slim to none.