This is not a 100% accurate description of 4chan. For one, on a lighter not, more often than not the woman in question was a guy trolling the community with images drawn from google.
Prior to the post ID system across the site there was also no real way to tell if the person posting was the girl in question, nor could they be consistently followed without being present on a site outside of 4chan. When you went in to one of the boards, you were anonymous to other users pretty effectively, so having your identity revealed as a woman was nearly impossible with volunteering the information. Without a user profile or a way to track post history, its very hard to determine if someone is a man or a woman.
Understanding 4chan, and specifically /b/ (what people usually refer to when they are talking about 4chan) is very difficult without having experienced it for yourself, but its not a necessarily sick or perverted act. Part of what belonging to the /b/ community was was understanding how to fit in to the circlejerk, and understanding that when you stepped in to the anonymous forums words were wind and you were to be as offensive as possible. Its supposed to be a caustic environment, because its basically a room full of people yelling.
That being said, the culture /b/ has is not something to take outside of /b/. The people who did back when I was active there were, to borrow a phrase, "the cancer that is killing /b/."
I also don't recall a woman being DDOSed or slandered for not showing her breasts, though I know many, many people have been DDOSed for reasons ranging from being the Westboro baptist church, to being an asshole of a boss, to be a feminist writer that /b/ disagreed with.
I suppose, if I had to pick a really good metaphor to accurately describe /b/, its a really fucked up exploitation film from Italy in the 70s that is also fascinatingly immersed in its own genre. The part of me that loves grindhouse and has an appreciation for Italian exploitation films as a subgenre adores it for being just so deliciously messed up and insane, but I would never, ever, EVER bring it to a friends house or show my parents it.