Because they have their lives back. I guarantee, if you got your hair back, you'd be too busy to check in all the time like you do now. I'd probably be gone...except every once and a while dropping in to show progress and encourage.
The dissapearance could be that it turned out to be sh*t, and now he is dealing with the doctor, since he disclosed the doctors name, he has no leverage if he post pictures that show what a sh*t hair transplant it was, so if the doctor does not give him a repair for free or the money back he might post. Just a thought.