Low success rate of body hair to scalp?

[Moosegel]

Various studies report success of body hair grafts to the scalp in the range of 80% to 95% for beard hair, 60% to 85% for chest hair, and a big drop down to about 40% for abdomen hair and back hair.

I have a lot of all of these types of body hair. To my eye, the ones on the chest and abdomen are identical, though I have greater density of them on the abdomen. They grow at least 8 cm long and have same or better calibre as my scalp hairs. (They might grow even longer than this, but I always clip them when they get too long.)

Why should the transection and growth success rates be so much worse on the abdomen hairs compared to the chest? Is it because the chest has a breastbone to make the skin easier to punch against when taking grafts? Unlike the abdomen which is soft and jelly-like?

And why do many doctors recommend against using back hairs, even though the back also has a backbone to make the skin firm, hence easier to punch grafts? A few doctors told me that the back scars badly, and yet I have seen various doctors’ websites in which they show successful transplants from back hair to scalp.

I’ve read a number of studies that claim successful body hair results using non-beard hair. Many websites like Dr. A’s also say they are successful with body hair. But then you also have doctors like Dr. Cole who said that only 25% of patients grow significant hair from body hair transplants.

And you have doctors like the ones at Eugenix advising against using any kind of body hair except beard. Are some doctors just more skillful at extracting chest/abdomen hair than other doctors? Or are there unpublicized issues with body hair? I think I read somewhere that they might regrow with thinner calibre than they had in their original location. Any truth to this?

How can medical opinions be so diverse about body hair?

Another question, can DHI be used on body to scalp transplants?

Would appreciate any thoughts on these questions.