Eh, no; your statement sort of gets at our state of knowledge, but it's overstated so dramatically that it's more wrong than right.

The research is at the level of being able to detect that there is some biological basis for (or at least biological correlate of) trans identity, but it's far from consistently observed. So, why isn't it consistently observed? Is it that the structural and/or functional changes aren't determinative but only provide a bias when interacting with culture? Is it because the patterns are too subtle for us to have picked them out yet given our relatively crude tools for measuring brain structure and monitoring brain activity? Is it because some groups just muck up their experiments (and which way are the messups?)? Is it because we're drawing a line between "transgender" and "not" when in fact it's a spectrum or multidimensional and if we could measure quantitatively instead of binning into two groups our physical/functional correlates would be more consistent? We don't really know.

I don't advocate for interventions that are known to fail. But I also don't assume that because we've found something that works better than nothing for some people that we've found everything we need for everyone who expresses any degree of dissatisfaction.