Tired talking points from subreddits that breed and repeat those points until those commonly going to them can do nothing but repeat those talking points rather than learning and thinking on their own.
Anita saying "everything is sexist" was a reference to her past self where she constantly acted like that and lost friends, learning to be a more decent person in the meantime. She was not literally saying "everything is sexist" she was saying that is how she felt after taking her first "womens studies" classes.
And they are not claiming everything is oppressive to women and minorities, they are claiming that male dominated areas like tech are, and/or that sites like reddit which DO have a lot of sexism in them have resulted in people leaving reddit.
If you want to talk down these people, if you want to appear inteligent and change minds, stop going to places that recycle these points over and over, or at least suppliment them with some sources from places like /r/gamerghazi. Even if you don't agree with them, you should at least take the time to read and understand their views.