This is again a highly misunderstood collar like the Choke or Prong collars. The mechanism of this collar is transmitting a vibration or very low electrical pulse using a remote at the appropriate stage as a corrective stimulus.
Pro: No need for a leash while using this collar.
Con: Can be misused with the higher electrical impulse to cause unnecessary trauma to the dog.
It is very easy for dog owners and professionals to be against any or few of the above collar-types without prior knowledge of what purpose or utility each of these collars uniquely serve. If the links of a prong collar are opened they can be used for pain-inducing purposes as they usually are by dog-fighting criminals and other punishment-based trainers. Similarly if a dog is tied somewhere with a choker or if the choke chain is used in reverse, the dog can certainly asphyxiated.
Hence, the best advice for a concerned dog owner is to do research upon their dogs breed and temperament before opting in for any particular collar. And no collar is meant to be on the dogs neck permanently. When not needed, the collars should be removed from the dog like when asleep and indoors.