You need to be able to show your clients what they are doing when thry are stuttering or using maladaptive speaking behaviors. If someone is using insertions or hanging out on a sound without moving on, they might not realize exactly what's going on. You need to be able to demonstrate all sorts of stuttering. It's part of the job. Also what did those students who refused to do the assignment think? If they did the assignment they'd be pretending to know what it was like to have a stutter?