After 19 years in the tech industry I would say (as a generalization) the women developers I have worked with tend toward the top of my list of the best of the best that I have worked with. What I have seen is male developers span the full full range from really bad to rock start amazing. While the female developers, maybe 95% are top notch or better with a very small number being mediocre and I can't think off the top of my head of a truly bad female developer that I have worked with.
My theory is that all of the misogyny acts as a filter and only really incredible women can get past all of the hurdles that men get to skip (gender bias in school, misogynistic hiring practices, less pay, sexual harassment in the work place, and on and on). Meanwhile shitty bro-grammer talks with another bro at big company x and breezes into a job and up the ladder in no time.
I think much of the bro-grammer rage you see and hear about is that the sea of shitty bro's are very threatened by the very good females developers they encounter. They can't beat them in code quality so they take to shit talking about them and writing brain dead manifestos like the OP linked to. It's a desperate and fearful hope that stronger men will sweep the scary women away before someone realizes what a fraud they (the bros) are.
And just to be super clear. Anyone can be a great developer (even bro's) with time and effort to learn and grow the skills required. It's sad that so many choose to spend that time and effort attacking their very skilled female co-workers rather than improve their own skills.
I should add a note that while bros these days get all the attention. The older generations of developers have just as many offenders. They just don't feel the need to tell the world so loudly so it can be harder to see from a societal view point. Not unlike old school racist republicans versus the new Trump racist that films and post video of themselves being racists.