It's still extremely harmful. Look at Jazz Jennings. He went on puberty blockers and therefore only ever grew a micro-penis. When he eventually got surgery to get a "vagina", he didn't have enough penile tissue to turn it inside out to make a neo-vag. The poor kid had to go through multiple surgeries, take skin off his thighs, and be in constant pressure/pain. He also will never have an orgasm, never have children, doesn't know what sexual stimulation or arousal is, etc.

Even if he didn't get the surgery and changed his mind, he'd still have a micro-penis and diminished sexual maturity/arousal.

And to top that off, he'll never be a woman no matter how many surgeries he gets. There is no surgery that can turn a male into a fully functional female, or vice versa. He still looks like a boy, even after all that. Telling children they can change sex is a lie.

It's a horrible life.