@pdorkin – Actually Koehler always said the cruelest thing you can do to your dog is to have to punish it twice for the same thing (I paraphrase). I have read all of his books numerous times and used them in structuring classes but I don’t recall ever seeing the line you have in quotes. I could be wrong, but it doesn’t sound like Koheler talk to me. He was however, a firm believer in discipline which is different from abuse although many now seem to believe they are the same.
From my personal experience over the last almost 40 years, when Koehler method was the predominant training used there were markedly fewer nasty, uncontrollable dogs.
Then marketing came into the picture, someone figured out that they could make money writing books on alternate methods and it is true, there are a lot of people making money on books and a lot more dogs surrendered to shelters because they do not fit in with the lifestyle (read they cannot be trusted, controlled) with their owner.
I think some alternate methods work, but they require much more time and energy to achieve the desired behavior. It seems to me that most people want their dogs to be a member of the family, not a 10 year training project.