All of my dogs are trained with a clicker. Do I use a clicker with sheep? Not often. Only when I see it might be beneficial. Usually, I just use a verbal marker. A verbal is a marker just as a clicker is. A whistle is a marker just as a verbal is. Body position is a marker. People get all freaked out by the click/treat thing. It works fabulously well with pups. My dogs will stand on their heads for me. I think it is because of their early operant conditioning with a clicker. Plus, it works marvelously well with shaping behaviors.
But, when I get to sheep, it's somewhat of a different story. Instinct kicks in. It's one thing to be standing in a yard without sheep and having a dog give you 100% attention with a clicker and treat. It's another thing to take this dog with years of stock instinct bred into him onto a field with sheep. I do not have 100% of his focus now. I try to maintain a 50/50 relationship at best :0) I want him listening to me, but focused on his job at hand.
People need to have an "open" mind. There is something to be learned from all aspects of training methods.
Those that feel a clicker has no place in training on stock, or one should do a correction first, command second, or command first, then a correction, etc. need to broaden their horizons. Different dogs have different needs. I have two dogs that want to team up with me most of the time and another hard nut that wants to do everything her way. These dogs need different training methods. What works for one dog, may not work for the other. If I was a closed minded person and wanted to stick to one way of training, I'd be in a world of hurt.
You need to figure out what is best for you and that particular dog you are training. And, you may have to do it by "trial and error" to find out what works best. It will only make you a better trainer in the long run. I dislike it when I hear so and so say.... I should "never" do this. Never say never. It will come back to bite you in the butt. Be flexible...take all input with a grain of salt and do what works best for you and your dog. :0)
And, lastly...no matter what venue someone is competing in, don't say nasty crap about it if it's not the venue you like. That is so cheap and so unnecessary. Makes for a very small minded, insecure person. Life is about having a GOOD time. Thank goodness we all don't want to do the same thing!