The answer is yes it can, but probably not forever or in every situation. I joined the programme not too long ago, and after getting used to deliberate dysfluency and the general techniques taught on the programme, I can certainly pass off as 'fluent' for an extended period of time in situations where my fear of stuttering is virtually at 0%. And believe me, I'd say I've definitely exhibited every type of stuttering out there in every situation- comfort zones and non-comfort zones. Now I certainly don't go for long periods of fluency in those comfort zones, as I'd be setting myself up for trouble down the line- and this has happened lol. The next best thing is the stage we call 'disciplined spontaneous', where you still use the techniques, although in a less exaggerated manner, and more sparingly. This is what would be considered disciplined spontaneous: https://www.youtube.com/watch?v=PIXmLyHz5xs. The people you saw were probably at the initial 'mechanical stage' where they have to limit their number of words per breath to gain that initial control. This most definitely is not the end goal of the programme.