Why? The evidence is weak to non-existent that it helps children, while the evidence that it creates permanent health problems is growing. Shocking, I know, that pumping children as young as 8 with puberty blockers and then hormones, followed by surgery might not be good for them.
Human beings practice medicine, and irrational enthusiasms, groupthink, and delusions can drive human beings. Eugenics was once well-established science, and frontal lobotomies were considered such a miracle treatment for mental illnesses or even mild behavioral problems in children that the inventor got a Nobel Prize.