Based on all the people I know who actually use Tumblr (only one or two), I'd say it's the bleak fucking truth.
There are people who are not that crazy. I mostly use the site to look at gifs of cute girls. But it's culture is very sjw.
The first of my Tumblr using acquaintances is a radical feminist who spends more of her time reblogging and sharing feminist posts on Tumblr and Facebook respectively than actually socializing. The kinds of posts she'd reblog/share are mostly about rape culture, the evils of patriarchy, how 'nice guys' act entitled to sex just because they're sad or annoyed at being rejected by somebody close to them they've developed feelings for despite the "friend zone" being a gender-neutral social construct, how women who dress provocatively, or heavily flirt with a guy aren't 'asking for it' and whatnot. The other one is more like the extreme fangirl who reblogs 46 animated gif recaps of the last episode of Doctor Who sort of crazy. Oh and she's mainly obsessed with the Pokémon anime and regularly ships characters.
I know that there are people like that on tumblr and I don't really understand what you're trying to prove. I you're saying that everyone on tumblr is like that I don't understand how a sample size of two is any help. And neither of those are unreasonable.