Not true, I'm afraid. Puberty blockers were only ever suitable for a select few trans kids for a very limited time.
The vast majority of trans boys get no gender care at all, yet still socially transition and go to school as themselves.
The vast majority emerge from that hellfire traumatised by bullying, coping with dysphoria - and still trans. Often having dropped out of school. Some get support, but most do not.
They weren't 'tomboys' to start with. They were trans.
Wanting the freedoms boys have, and rejecting gender stereotypes, is incredibly common among cis girls. Being trans is not, and many trans boys are very gender nonconforming, meaning they reject stereotypes in work, clothing, behaviour etc.
You weren't trans, and they weren't tomboys.
I'm sure it suits you to believe that surviving school while trans, and going through a traumatic, unwanted puberty, is easy. It really isn't, even if (as is not common) a trans child has parental support. There is no community sitting with a trans child on the daily school bus while literally dozens of kids gang up on them. None to walk the streets and corridors with them, or comfort them at night.
Trans boys grow up, in the vast majority of cases, into trans men. It is a difficult, horribly risky existence with online agitators constantly spreading misinformation that directly enables street violence.
No one would be trans unless it meant everything to them.