Well I don't know what you are visualizing while reading my words but under some circumstances I think this is completely appropriate. You seem to be associating my use of physical touch with pain or punishment. It is neither, it is just to get their attention kind of like, "Hey, (tap, tap) I'm talking to you". The bigger and more obsessed the dog, the stronger the tap. But it does not hurt them in any way.
When I feed my neighbor's Rottie when she is on vacation, it will have usually been awhile since I last saw him and he will be back to his old bad habits (she has no leadership role in his eyes whatsoever so it's her fault, not the dogs fault). When I walk into the house with anything he thinks might be food, he will immediately try to knock me down and take it. I am not his owner nor full-time trainer and I only have a few seconds to make an impression on him. I don't have the luxury of time with him to train him using positive reinforcement. His owner won't do it either so it is what it is. Nobody else in the neighborhood will even get near him. I'm his only option when she leaves but I don't have time to "train" him. That is her job so, basically, it ain't gonna' happen.
If he starts to charge me and doesn't immediately respond to my assertive posture, and a vocal "No!" and back off, and if he is just obsessing over whatever he thinks I have for him and not paying attention to my direction (it may only be a set of keys in my hand and not even food), I give him a little stab on the side of the neck. It's just enough to get his attention and make him look at me. It's more for shock value than anything, it doesn't hurt him. When he does something right you'd better believe I praise him. But when he gets obsessive, I will use touch to bring him back to center. FWIW, I'm the only person in the whole neighborhood who he listens to, including his owner, and the only person who can play with him and walk him without things getting out of hand. But I don't see him very often and it usually takes me two days or so to get him to understand that I don't play the game his owner plays and to remember how to behave with me. Two or three days is usually all I have at the most and those may come months apart.
I'm glad you have time to devote to your dogs using nothing more than positive reinforcement. Obviously that is the best option whenever it is practicable and it is the main technique I use on my own dogs because I have the time to devote to them. But it is not always an option when you are dealing with a dog you are not around all the time or one that is aggressive. I can't change my neighbor's relationship with her dog or convince her to train him properly. She's an idiot. She gives him LOTS of positive reinforcement, but always at the wrong time so he walks all over her and he's totally confused. I won't let him dominate me but I don't have time to work with him properly. He has to understand me immediately and if I don't get the response I want from him because he is distracted, I will use physical touch to get his attention. Granted, it should be a last resort, and I'm not implying to the OP that is should be used casually or without thought. It should only used on very troublesome dogs but I see nothing wrong with it in some of the situations I've faced. I don't think there is anything wrong with using different techniques for different circumstances and different dogs. Physical touch is just another tool to use in certain, difficult circumstances when you don't have the luxury of time, or the kind of relationship with a dog that permits a more gentle approach. As long as you aren't hurting them or intimidating them, I see no problem with it.