That is not a feminist assumption. That is a villification of feminist beliefs. A maligning.
I've never been completely powerless and believe me, I'm no angel. No matter how hard I'm pressured to take on that persona. Just ask my mother. She'll tell you all about it.
That said, certain things in life ARE made harder for me for no other reason than my gender. In a lot of ways my gender is a straightjacket, or like being ensnared by a boa constrictor. You can't breathe and the pressure just crushes.
Here's the truth of feminist beliefs. We recognize that it's the same straightjacket or ensnarement for men, just in different ways. It manifests differently, in other words.
In the same way that not all "Christians" are actually living a Christian life....not all "feminists" are actually living a feminist life. Sooner or later, they'll expose themselves. You have to be prudent and use discernment to tell the difference. And don't forget about the bots either. You have no reason to trust that just because someone, usually anonymous, on the internet says they're a feminist that they actually are. Let them prove themselves first by comparing what they're saying against actual feminist beliefs over time. Same as we have to measure "allies" and other men claiming to not be misogynists over manosphere rhetoric, etc.