When did parents become so desperate for their children's approval that it prevents them doing their jobs and acting on their consciences properly?
When their children started expressing their disapproval by cutting themselves... or by taking anabolic steroids and other wrong-sex hormones and getting their tits or genitals hacked off... or by threatening suicide.
It's not that parents are rejecting their trans children, it's that children are deciding they are trans and rejecting their parents. Because telling your child it's a bad idea to self-sterilise is like, you know, so transphobic and so cis-normative.
The suicide narrative - give me what I want or else! - has a lot to answer for. So does the "parents who don't affirm are just ignorant transphobes" narrative. Both of which are peddled by - tadaa! - Mermaids, in what is not at all a coincidence.
If people have been "trained" by Mermaids then even if they reject the ideology they're still hearing the threat about what their own children will do to themselves if they express their views.