It would seem to me, though I am not a shrink, that the longer a delusion is fostered, nurtured, even, the greater the level of disillusionment when reality rears its uncaring face.
That tremendous shift in perceptions, and the unhappiness that comes with finding out that no amount of wishing will change biology, no amount of mutilation, be it chemical or surgical, will turn someone's little prince into a princess.
If that delusion is fostered into adulthood and through surgical mutilation, the shock of waking up to find that it was all lies must be profound. That those trusted wanted to write an article on surgical technique, or simply wanted the money or some sort of prestige at their expense, would be an embittering experience at best, but the longer those delusions had been nurtured and fed, the more devastating that awakening. The alternative is life in some fantasy world where life in just a series of ongoing lies, hardly the fertile medium in which to grow happy.
Just stop it, don't feed the delusion, and the sooner the better, especially with those who are at an early age. Save them the eventual (if not present day) misery they will encounter along that path, and the pain of irreversible physical damage.
If we changed the doctor's name, to Mengele and placed these practices during the 1930s to mid-'40s in Germany, they would be viewed with horror, and rightly denounced.
Painting the rooms with bright colors and having a big screen TV does not make this any less the medical monstrosity it is.
I am not including the surgery for those rare few born whose gender is truly in question, but that would be assignment, not the re-assignment of gender.