This is a really common response, and I do honestly empathise with it because for most people (me included most of the time) in everyday life there's not really any need to think about it too deeply. Like you said in another comment "A child can tell you what a man and woman are."
But can they? Or can they just point at people and guess, with about the same accuracy as you or me? They probably can't _actually_ tell you what a man and woman _are_ in any useful way any more than most grown-ups.
Like you agreed in that other comment too, there are some "extremely extremely rare" cases where a child would probably say they're a man or woman but their chromosones aren't what you'd expect.
That highlights that chromosones aren't really a deciding factor though right? The child isn't using chromosones when they decide, and I've never been asked about my chromosones, or heard of anyone else being asked about theirs outside of a hospital.
So to answer your question, I don't think anyone is denying biology, it's just that biology isn't as relevant as it might seem at first thought.