I used to have a problem with that idea too, until someone pointed out that puberty is an irreversible process with major consequences. The fact that everyone goes through it is a bit irrelevant; if it was happening to someone over 18, puberty blockers wouldn’t even be controversial.
As a parent, what to do? I look at my 2yo daughter and wonder if I’ll have to support her in a decision like that one day, or go against her wishes just because she’s 11. If there’s research indicating that delaying puberty doesn’t have major long term harm, then I’m more likely to endorse puberty blockers.