I think that the reason this all sticks in the craw of some women and most especially some feminist women is that:
Many women come to feminism when they are girls. I was a feminist before I realised what the word was, and when I heard what it was I knew that was what I was. The reason I felt that way so young was because my external appearance was very feminine - small slight build, long blonde hair, big blue eyes. But that my personality was such that I was interested in "boys" things - I was good at and enjoyed maths and science, playing with lego, reading "choose your own adventure" books etc. My mum was forever making me do ballet and putting me in "pretty" but uncomfortable clothes and fussing over my hair. I reacted to all of this, by developing an idea that girls should not be pigeonholed! And I was a feminist.
When I got older and the constant appraisal by passing men, the catcalling etc started by god I HATED it so so much. And when I was older still, A Level, the fact that people (men and women) reacted with frank disbelief to my taste in films / books / hobbies and the subjects I preferred to study.
Anyway. That was then. I knew it was wrong and I became a feminist.
Now, I suppose I would simply try to identify my way out - I'd be agender. And, the issues that have plagued women and girls everywhere for ?all time, would not be my problem, would they. And the people who are subject to them - well there must be something in them that likes being treated that well otherwise they would identify otherwise, right?
So, I think this is why so many women and feminists in particular are highly pissed off.
And then there is the problem of language. If I want to raise funds for girls in a particular part of the world who are being denied an education, for example, what words do I use? There are none, according to the new rules.