Living by Hanlon's Razor isn't innocent, it's cynical. Also, it's not innocence to realize that a thirty something woman claiming to be "squirrelkin" is not true.
You've also got to remember that Poe's Law isn't just "they're being ridiculous but being taken seriously", it's also got a bit of people joining in not realizing it's ridiculous. Michael, from VSauce, talks about how this applies to The Flat Earth Movement, which makes a decent parallel to a lot of what I've seen on Tumblr. It's not all satire, but most of it what I've seen as "SJW" posts falls into three categories:
People saying reasonable things that they think will make the world a nicer, friendlier place (and of course a lot of Redditors hate that and call it "censorship" if they're asked not to call people faggots or it's suggested that maybe geek culture is sexist or exclusive or creepy)
People saying ridiculous things, either to make fun of the people who say reasonable things or to make fun of the people who take everything as an attack (I'm 90% certain that most "Otherkin" shit is a joke, made to mock trans people originally)
And last, people who have had their beliefs attacked so often that they're radicalized, people who've misunderstood things and become fervently in support of them, people who really are the stereotype of a Right Wing Religious nut, but on the other side. This would be your people who think all men are evil or TERFs or people who took Dworkin's "all sex is rape" statement seriously.
Reddit--and 4chan and SomethingAwful and wherever else you go on the internet--seems to think that the last one is the largest group, the middle doesn't exist, and the first is part of the third. That's not how it really is, though. Finding examples of the third is easiest, but that's because it gets shared around the most, just like it's easiest to find MRA blogs talking about how the government should subsidize prostitutes for lonely virgins and how women should be kept in rape camps and used for sex and breeding and be turned into food when they hit thirty. Reasonable doesn't get shares, likes, or tumbls. There is a problem with Tumblr, but it's the same problem that Reddit has, that Facebook has, that everything else has. It creates a fishbowl where you only hear who you want to hear. You start thinking certain views are the only view out there. For instance, go to /r/OneY and you'll see a ton of people claiming that women are the cause of all of men's problems and that men have worse problems and that feminism is over and all women want now is to take power from men. Try to engage with them and admit that men have problems, but that women still have less value on a societal level and you'll get angry, impassioned, and poorly thought out hateposting where most of them have no idea what women have to put up with. I mean, shit, look at the dichotomy of responses to this question I asked on r/rpg.
Of course, here's the kicker, and why it's cynicism, not innocent naivete: People don't change their beliefs when they're confronted, especially not violently. They double down. That Tumblr girl who thought that men were mean and should be kicked out of power? Yeah, calling her a cunt, telling her you're going to rape her, and sending her death threats is not going to change her mind, it's going to strengthen it. Just like telling that douchebag who can't get laid because he's a hateful person that he can't get laid because he's a shithead isn't going to make him stop being a misogynist.
And that fishbowl of the internet? It also encourages that kind of attitude. And the world we live in is becoming more and more striated and stratified and segregated. People on Reddit are amazed that anyone would ever believe Glenn Beck or Bill O'Reilly, but they do. And they live in a different fishbowl than most Redditors. And thanks to 6000 cable channels, OnDemand, cord cutting, Facebook algorithms, Youtube suggestions, Tumblr and Twitter hashtags, and everything else about modern society, you might never interact with them and they'll never interact with you until your fishbowl touches up against the glass of theirs and you get a hint of crazy. Doesn't matter whether it was real crazy, satirical crazy, or misguided crazy, you just see it as crazy crazy.