Imagine, if you will, that every clothing store everywhere stopped selling any sizes but medium and large. I would imagine that a majority of people would be okay with that. It would make buying clothes easier, and most people probably fit into medium or large and there would be more of their size available, so cool.
There would be, however, a large number of people not well served by this decision, and they would fall, in the main, into two groups. On the one hand, you would have people like me, who wear a small or extra small. I can certainly wear a medium, but it looks terrible and I'd have to seriously invest in belts or spend a lot of time learning advanced tailoring techniques. I'd probably have trouble getting dates or professional jobs due to my newly created sloppy appearance, but I could get by.
On the other hand, you'd have people like my husband, who wears a size larger than large. He simply could not fit into a large, let alone a medium, and no amount of tailoring or belts would help. He would have to either wear obviously home made clothing (after all, everyone would know he didn't buy clothing that large at a store) or stay at home naked. He could not get by.
If case you haven't figured it out by now, I am using clothing sizes as a metaphor for binary gender in Western culture. You can be a woman or you can be a man, that's it. Medium or large, man or woman. In reality, there are about as many genders as there are people, and most people are not all of one thing or all of another, any more than most people are exactly a medium or exactly a large. Most people are going to find one size a little too small, the other a little too big, but whatever, close enough. I identify as a woman, but not all womanly aspects really apply to me, but I'm definitely closer to woman than man, so whatever, close enough.
As in our clothing metaphor, there are some people who are close to typical gender binary and others so far outside culturally determined typical for their sex/gender that they can't simply say "whatever, close enough". Some of them are like the smalls in our clothing example. They're women who are a little too butch for comfort or men a little too effeminate to be reasonable*, but in a big enough city, in the right atmosphere they get by. Some people, however, are like our 2XLs: the gender binary simply does not fit them no matter how hard they try. You simply can't fit 10lbs of potatoes in a 5lb bag, and a man who identifies as a woman in our gender binary is the 10lbs of potatoes.
So, to continue my metaphor, imagine the argument going like this: I've always been bigger than a large and have had to deal with that my entire life. I've always been the subject of pointed fingers and bullying, always had trouble getting jobs and finding a place to fit in. You, you Johnny-come-lately to the world of binary fashion, only recently gained enough weight to be an XL, and now you're going to tell me how hard it is? I'm 6'8", I couldn't lose enough weight to fit into a large, you could just go on a diet. Cry me a river, asshole.
Oh, so you're a trans woman, are you? Was somebody stuffing you into pink dresses as soon as you were born? Were people shoving Barbies into your chubbie little fingers on your second birthday? Really, you're a man. You still have a penis and you could present as a man and not have to deal with the patriarchy bullshit ever again. Bleed me an ocean**, jackass.
The best answer, of course, would be to start the revolution that ends with me as Empress of the Entire Freakin' World, at which point I will abolish the gender binary and end the patriarchy. It will be a gender free-for-all in which public restrooms will be big rooms with stalls that have floor to ceiling doors with deadbolts and open to all and driver's licenses no longer carry a notation regarding "sex"- other than "yes", "no" and "kinky". The Empire's various police forces uniforms will be fabulous, Hessian-inspired and include skirts over pants just to cover all options. On alternate Tuesdays, everyone will wear bras and high heels and the following Thursdays, we'll all wear ties***.
Until that happens, however, arguing whose patriarchy pain is more authentic is entirely missing the point. And as long as we engage in these arguments, the patriarchy wins. We don't want that, people.
*In a societal sense, not my opinion. I don't care what other people do in that realm and I was surprised when I learned other people did.
**If you're not familiar with Acidbath, I don't know what to tell you.
***Perhaps the world at large should have been a little nicer to me.