I have never used force or discipline for obedience exercises... my girl shuts down completely if I so much as tell her "no", so she doesn't even get that Some timid dogs do have issues with the Stand For Exam or perhaps the stimulating environment but the ones I know who are competing generally do very well and it helps build their confidence a lot Agility is also a great confidence builder.
The worst that happens to my dog is that if she decides she doesn't want to work with me (pretty rare) she might get a no reward marker ("oops") and we try again. Or I might release her and ignore her for 10 seconds... which is technically an aversive as she hates it but it's better than rousing on her
Sorry, bit of a life story there
Just wanted to add, I do agree that competition obedience is not for everyone I don't compete with my older dog because to be honest he would prefer to be lying on the soft bed at home. So that's what he does!