I can't say I personally agree because I have personally seen much the contrary within both feral and pet dogs. I really want to find a study that measures the trainability and happiness levels using all the different methods.
But this is exactly what the last study I cited DOES show -- and there really are only two methods -- punishment/corrections vs reward/positive motivation. The study cited was also published in one of the most prominent research journals in its area. I'd also suggest that casual observations by those who are not familiar with what species' behaviour (understood by a trained specialist) means can very easily assign the wrong interpretation to an area of study that involves a professional degree and many years of scholarly and field study which no one I believe on this board has (though some of our trainer members like TKC DO have several years' training and international professional qualifications). Untrained casual observation of packs of dogs (and there are no true 'feral' packs except in Africa so you are not seeing wild behaviour, you are seeing roaming former domestic dogs) is just as likely to be completely wrong as if I went out in the field to do your professional job without your qualifications. In addition this board is full of examples of how interpretations of casual behaviour very often is easily and wrongly interpreted -- going by how many times people assume their dogs are saying x when basic behavioural knowledge (of the type that sadly doesn't get onto as many TV shows ) would indicate they are saying y -- for example people who with the best intentions think their young dogs must be deliberately opposing and defying them because they haven't learned (choose the behaviour) housetraining, to sit, to lie quietly, to stop barking, to get off the sofa, to not fight over food. Many of these behaviours result because 1) the dog is too young to know yet to have learned a behaviour well enough to be reliable; 2) the owner has not put the time or consistency into training; 3) the dog has been 'taught' in such a way that the results are the opposite of what is wanted -- eg the dog is scolded for peeing inside and hence its obvious conclusion is -- I get scolded if I pee when someone sees me so I will do it secretly when my owner isn;t in the room -- not 'gee, that must mean I should go in some other location', a far more subtle distinction.
And given that a dog has absolutely no problem telling a cat from a dog -- why in the world do we have this ridiculous idea that a dog looks at a human and says -- "gee, that must be a giant dog and my leader of the pack!'. If a dog doesn't relate to another four legged animal about its same size, why are we so self-centred as to believe a dog is so clueless as to confuse a human with a lead pack dog?
One thing I have learned over a lifetime of owning dogs -- and especially from having spent so much time with professional trainers in the past 6 years -- is that dogs are not stupid. They do -- like 'non-pack' animals like cats or tigers or horses -- respond so spectacularly well to positive methods training used correctly that this type of training is used in every area in which animals must be trained with precision for predictable performance -- eg Hollywood, performance show animals, etc.
Dogs like any animal or humans do recognise calm positive leadership and guidance, and just like people, tend to work especially hard for a reward, be it praise, a nice meal, a salary raise for people -- or -- yes, praise -- or attention, or food if a dog.
NB the study doesn't argue that dogs do not live in pack structures at all; it argues that basing training techniques on ideas of what some imagined alpha dog does to maintain control (and that is the whole problem -- dog leaders do NONE of the TV trainer poking, hissing, alpha rolls etc to act as leaders) is not just wrong -- because it is based on totally wrong ideas about dog pack structure -- but dangerous. Dog pack leaders are not aggressive, they are benign leaders. And often there is more than one leader depending on the activity/task.
In general, it is wise not to make the common and significant error of assuming casual observation of our pets equates to professional observation and study of same -- especially with preconceptions of what behaviour 'means' taken from watching television programs and absorbing what has been popularised in pet ownership books despite being ~LONG DISCOUNTED~ in professional animal behaviour study.
I have posts in the training section and library with more info and links on why these studies were simply wrong from the start.