One other issue when it comes to a therapeutic situation, which should not be over-looked, is the impact of someone's belief in gender identity on others.
It might be considered that focusing on others is not the point or goal of therapy, and that is true - but if you are constructing a identity on the foundations of a belief system that most peole do not share, and who most likely will not be able provide the required affirmation for - then you are constructing an inherently fragile sense of self - certainly if requiring others to use pronouns or to rely on them recognising you as the sex you want to be is the goal.
A healthy, well adapted sense of self is resilient and fairly stable and does not depend, overly, on continual affirmation or recognition from others If you think your existence is under threat because others do not share the foundational beliefs in gender identity, and so continue to recognise you as the sex that you are - that is not a good place to be.
I suspect genderists must know this - hence the need for total control and for continual affirmation. 'Gender' after all is a social construction ( even if you believe it is innate - you cannot locate it, describe it accurately, or prove it) and the queer theorists knew this too. In playing around with gender or with the performance of gender, the idea was to push the boundaries of soociety and 'queer' them. 'Gender' becomes a transgressive act with revolutionary intent.
The problem with utopian ideas, though, is that the world and other people tend not to conform, and we are inherently social creatures requiring workable relationships with others.