I never thought of female characters like Ellen Ripley or Shosanna Dreyfus as Mary Sues because they were well-written characters with background stories that justified their tough personas. More importantly, there was a lot of focus on exposition, so it was completely clear to me as the viewer what their motivations were. I never once thought anything about their gender, just that I was watching a badass character earn their revenge, and I was rooting for them all the way. Most critically, they had to overcome significant adversity to get there — their badassery wasn’t just handed to them on a platter because they’re a woman and stamped their feet and went blue in the face like Veruca Salt.
The main problem with modern heroines is that there is no real adversity being overcome. Their personas mirror the already established feminist narrative, specifically that the adversity is intrinsic to their gender. Therefore, by simply existing and not being demure little wallflowers, they’re earning their badassery by default. The problem is that, to those of us who don’t believe in the mystical existence of the patriarchy, these so-called heroines just look like spoiled brats whining about an imaginary friend that won’t let them have a turn. It’s not entertaining, there’s nothing heroic about it, and it is antithetical the entire point of superhero movies — they are supposed to be allegorical figures exemplifying all of the best human traits in overcoming significant adversity. They’re supposed to be something to aspire to, not something to be scorned.