Because the treatment for other mental health issues in children and adolescents doesn't usually include a pathway of medications for which the long term effects are unknown and the effects of which might be irreversible. Instead it usually includes exploratory therapy - which you dismiss as conversion therapy. All for a state of mental distress which resolves without medication or surgery in most children by adulthood.
It's not good enough because it is questionable whether children of 11 can give informed consent to a pathway of treatment that can leave them sterile and with no sexual function, ie puberty blockers. Which is why several countries have reviewed their protocols on using them with kids.
This view is because you can not accept that gender incongruence is not labelled by the WHO and other medical experts as a mental health disease. This is because you have no cognisance of your own self in relation to gender identity. Your assumption (you are spectacularly good at those) is that it therefore can not exist, but are firm in your vague belief that you are the 'normal' one, and people who are cognisant of their own gender identity are therefore diseased. Therefore the world must outlaw normality to allow you to fit in. Self-awareness must be contained as there is evidence that it may be spreading. For you it is a social contagion.
In the queer community, we've had a lot of experience of self-knowledge, and self-doubt caused by others telling us we are sick. Often those who shout the loudest are the ones firmly in the closet, in a deep state of denial. If that's you, then you are so far back in the closet, you're in farking Narnia.
Yes, young people have experienced confusion about their sexual identity, but increasingly incremental steps in some social acceptance brought gay people coming out in increasing numbers. The more social acceptance there is, the less people need to live in fear, and the greater the load on their resistance to mental health susceptibility.
What the culture wars that reactionaries like you promote is social exclusion in fear of cruel people like you who subject them to prejudice and persecution. This leads to increasing levels of anxiety and distress. Panic attacks become frequent, along with depression, tendencies for self-harm, suicide ideation, and the numbers of casualties of all of these things. The suffering is not restricted to those individuals, but to those who love them and care for them.
While you claim your cruelty is necessary for women's rights and your reliance on the argument that only a woman can bear a child, you completely manage to overlook the suffering of women who are faced with nurturing their children in the face of this societal cruelty that you advocate. You also manage to portray that men are the perpetrators of cruelty to women, while playing down the level of cruelty perpetrated by women on each other - almost as if in fact there is realisation that you are one of them.
