Yes there are a number of current cultural assumptions that have allowed the acceptance of trans as a real thing.
One is the idea that you have a right to be happy and happiness is the goal. This belief means that no distress or discomfort should be expected to be tolerated. And particularly not for an extend periods (like maybe a during puberty).
Another is that identity is an internally driven concept which is innate rater than a socially constructed concept agreed between people. This in fact is one of the biggest assumption changes which isn't discussed enough.
Another is the shift in how we view children, child development and childhood and the move to giving children more autonomy. 'Child voice' and children know what they want ideas are now prevalent in a way they weren't 30 years ago when children were viewed as developmentally unable to make decisions and adults presumed authority over them. This type of thinking led to things such as Gillick and, in my opinion is also central to understanding the grooming gangs phenomenon and why it was ignored. But t's also central to the trans thing.
You then get people who want to promote queer theory, upturn all norms, especially around children, and the ground is ready for them to use all these 'new' assumptions:
Being your authentic self makes you happy and no one should be allowed to stop you being it.
So you must have the drugs you want to be happy.