Thanks for bearing with me . I will go through this quickly but I think you are going to have to check back a fair bit when you try to make sense of my garbled response.
There are 4 part to Positive and negative reinforcement . It goes without saying that positive is the ADDITION of something nice (+R)(a stimulation) and negative is the REMOVAL of something not nice (-R) still (a stimulation)
We need to move into construct theory a bit . If things happen to your dog randomly they are not engaged in any learning it does not make sense. So if I chuck a treat on the floor and my dog didn't see me he doesn't associate finding it with anything. He just thinks he happened upon some random treat. So it was ineffective therefore negative there was no reinforcement of anything . No learning took place at all. Similarly if I come home and shout at the dog for ripping something up. this too is negative (punishment) because no learning took place. Many people say their dog looks guilty well if you just watch him interact with another dog who is acting aggressively - S/he is simply saying " I am no threat to you" this is not sorry. It is a simple placatory tool. All that he actually knows is some days you come home in a Foul mood.
So the cage is not a bad place but it is a restraint, however you care to view it.
I restrain my dog a thousand times a day. I shut doors and I put her on a lead. I e. I limit what she can do. Similarly I restrain my horses and ponies by putting up electric fencing (or whatever) it is still a restraint. MKG said he was not happy with the use of a cage . Fine everyone is entitled to choose acceptable and unacceptable practices.
My only angle is understanding. We just need to be singing from the same song sheet.
As I recall the initial post was somewhat vague. In fact the poster never said anything about previous ownership or experience so many of us kinda assumed that there was none but we don't know that it just did not say.
There are stack of competition dogs out there that are trained purely by positive re enforcement , though I suspect MKG is not one of them. He may not like the idea of training with a cage but I bet he would agree he is not +(R) pure.