They do it to silence women who want to talk about their own issues. An example:
You can't say "women can give birth" because that excludes trans men who can give birth and hurts the feelings of trans women, who can't give birth. So someone who wants to talk about the category of people who can give birth who wants to be trans-inclusive changes her language and says "biologically female people can give birth." But wait! Trans women are biological women! This is what leads to stupid, genuinely dehumanizing language like "uterus bearers" and "bleeders" which does, funnily enough, end up excluding women who have had hysterectomies and/or gone through menopause who might still be relevant to the discussion because they've given birth in the past.
There is nothing practical about any of it. It does not create clearer categories or lead to less "exclusionary" language. They take the words we use, and then they take the words we use in place of the words that they took, and they don't stop until we shut up. The only possible recourse is to retroactively not give the inch. That way, maybe we can get the mile back too.