Cutting any part of the plant off is stress. The plant then sends warrior immune system helpers and isolaters to seal the site and perhaps stop infection. Plant power is finite, if power was used for healing, power was taken from somewhere else. the yield suffers. There is no denying this. I don't buy this technique, if you can call it that. It is plant stress induction.
If you cut the tip of your finger off while chopping some carrots for a stew and have a big zit on your face same time, after you get the finger injury dealt with, this zit will take longer to disappear then it would without the finger injury as finite immune system power is spread to do multiple things at once. What do you think is taking place inside the body when injury occurs, this is same as plant, energy is redirected away from growth, same as if child had major injury in grow phase, he can be stunted child, energy is finite, not infinite.