Why? Is it because the medical transition itself is barbaric?

I think we all know what the objection here is, but I'll go ahead and say it anyway just to be clear. They think it's barbaric because it quickly becomes the (pardon the unintended play on words) cutoff point between the mentally ill who have some wires crossed up in their heads and the AGPs (and their female counterparts) who just want to justify, display, and force participation in their fetish. And it's plainly obvious that the vast majority of troon shit is being driven by the latter; the former are mostly too busy actually suffering from their issues to play stupid games based on them.