the harness I use is a step in harness. It has no contact with the chest. there are 2 leg holes, and a strap that is on the belly between the legs. you then bring the 2 sides up on top and clip the leash to hold it. It is very different from a pulling harness.
So if someone came to you with a young puppy for training, and did not like to use a training collar but wanted to use a harness you would tell them different? I agree that pups are impressionable... but they can learn to walk nice without using a collar. Why would a 7 week old puppy not pull so hard with their neck as with a harness? And a training collar is meant to get tighter as they pull, so it is a negative response to pulling, do you not think this could harm a VERY young pup, or small delicate dog?
Perhaps we are saying the same thing I don't know.. but I know I said going outside for several romps a day off leash would be better than doing a walk with collar and leash at this point.
The thing is with dog training, no one, and no link is really right. There are many ways to do it, and many wont work for someone else. If someone chooses a harness it is not right to tell them they are doing something wrong, and will create problems for themselves. Any positive training should be able to train any dog without relying on equipment.