Those women's necks aren't stretched, their entire torso has been pushed down and compressed. There have been studies where they've actually removed the rings and took x-rays. They found the spine to be the same length as a normal person, proportionally speaking. Their shoulders and entire ribcage were compressed like those women with a 15' waist from wearing corsets most of their lives.
The lip plates and earlobe stretchers are a real example of tissue expansion, not "long-necked" women