Don't know why I didn't see this earlier... oh, I know, it's because I deliberately avoided most of the ones that weren't full of naked men.
All the Stupid Angry Girls are there now. Like their older Livejournal sisters, they spend their waking hours scrutinizing places like Jezebel for articles they can use to express their dismay at how the world is so screwed up. Most of these Stupid Angry Girls would claim to be bisexual, because being part of an oppressed minority group gives them some kind of validation to mask the brutal truth that, in reality, their "activism" and "efforts to change the world" rarely go beyond flame wars and mass swarming attacks within feuding communities. Occasionally, they may be spurred hard enough to flood the comment section of some article that offended them with indignant ranting. But most of the time, they stay in their pens like angry cows that, perhaps, know that they would be laughed at and ridiculed if they dare to venture on their own into the big scary online world outside the echo chambers of their Tumblr rings.
Claiming to be bisexual also allows them to fantasize about having sex with Benedict Cumberbatch without feeling guilty about objectification of the other sex while at the same time, being bisexual also means that they have "cred" to write "real" fanfiction about their favorite gay men having sex with one another without coming off as fetish freaks.
Their language veers from one extreme to another. Mention an ugly-hot guy (current meat of the day: Benedict Cumberbatch or Tom Hiddleston) and they would go EEEEE, SQUEEE, MY OVARIES ARE EXPLODING. Mention these men with another man they fancy and they would go I SHIP THEM SO HARD. Mention them with a woman and they go I HOPE THE SLUT DIES. Point out their slur and they would go YOUR CIS PRIVILEGE IS SHOWING SO QUIT MANSPLAINING YOU MOTHERFUCKER NOW FACE THE WRATH AS ME AND MY SIXTY TUMBLR SISTERS SWARM YOUR PLACE AND DOX YOU OUT.
But point them to some place where someone is making an off-color joke or being a buffoon, and they would break out their college gender study and sociology textbooks, where all the important words like "cis", "trans", and "how to call people assholes while sounding like a pretentious first year sociology student" are highlighted for easy copy and pasting. They live in a world where heterosexuals are all scums, all hot men should be homosexuals as they shouldn't be sleeping with other women if these Stupid Angry Tumblr Girls aren't getting any themselves, and all straight cis women should die in a fire.
Needless to say, avoid them. AVOID THEM. Stick to Tumblr pages that are full of images of naked men instead.