The prong collars that are legal in australia have flat tabs on the prongs, like fingers, not spikes. I have seen dogs try to lunge wearing one, and their neck remained intact not damaged.
I see it like a tool, similar to a head halter, the aim should be to control the dog enough to train the behaviour you want, and then wean the dog off the need to be wearing it. Following Susan Garrett's methods for head halter - should take around a month.
I 100% disagree with what those words that dog fanatic posted say.
Sometimes when a puppy has not been raised correctly - or has had some trauma through no fault of its own or its owners - a prong collar can be a very useful training tool to train what you want the dog to do - as opposed to punishing it with yank and crank on choke collars. Or just not taking it for walks at all because nobody can control it.