> Let's first be clear that gender dysphoria is a real thing
To be clear, the pain someone is feeling is real but the "reality" of a condition is a bit of an unclear concept. We can't really address this until we try to control for the gendered expectations of the sufferer, their surroundings, and any observers. Suzie Green of Mermaids has said that some of their motivation in transing their son as a toddler was his father's discomfort with some of the toys he was playing with and the homosexual connotations. Likely if the boy had tolerant and unbiased parents he'd be happy as a man, and thus it's unlikely he truly had "gender dysphoria" unless you count whatever his parents conditioned into him.
> and transitioning has been a very real solution for many people
Again, hard to say given that the decision probably was not made in isolation from heavily gendered expectations. There's reason to think that removing those expectations would have made them at least as happy, if not more.
> Transitioning is [...] treatment, and not [...] an assault on anyone's cultural, religious or political beliefs.
For an adult it's a personal choice and we should have pretty wide latitude in things that only impact us. It becomes a societal and political issue when it's brought into schools, or when males are given access to women's spaces and opportunities.
> And if it really is happening more to girls than boys, maybe consider if cultural sexism might cause some women to not want to identify as such anymore. Especially in the face of issues like rape, bodily autonomy, but also acceptable jobs and behaviours. Maybe we should be more tolerant of cross-dressing.
Errr, that's the wrong takeaway. If a woman wasn't going to get promoted then her putting on pants won't help, and if she was going to get abused it wouldn't trick her attacker. We should work to remove or mitigate those problems so she doesn't feel the need to hide her true self.
If a woman is thought to be able to avoid rape by dressing like a man and/or having surgeries to reduce her sexual attractiveness then women will be thought to be asking for it ("How was she dressed? Did she still have her breasts?") for not doing those things.