Those poor kids have been sold a lie by parents, teachers, social media, family and friends too lazy to dig in and help them. No child is born in the wrong body. There is no such thing as a trans child, just an unhappy one. If your child is unhappy about his or her body then find out what the real problem is. They are likely to be ND, or LGB, have MH issues or have experienced some kind of trauma. Help them come to terms or get help for that. Don't spin them a fairy story about being born in the wrong body and send them off into a terrible world of medication, surgery, loneliness and MH issues.
The women of Mumsnet you are complaining about are the ones who want a happy, healthy future for these children, free of endless confusion, hormones and drugs, which damage bones and brains. No one is jubilant about what's happening to what you call trans kids.