Many of the worst things about (the bad parts of) the social justice left are the result of it being too authoritarian, not too liberal. Too much like religious fundamentalism, not too secular. What follows is an incomplete list of such problems. I think I’m right about at least 85% of my claims. This list is not meant as finger-pointing, but a list of failure-modes to try and avoid.

• Creating community hierarchies based on level of purity and virtue
• Judging level of purity and virtue based on numerous irrelevant factors, like their personal language use, media consumption, clothing, emotions, friendships, relationships, and sexuality, as well as unquestioning acceptance of certain ideas
• Controlling people’s language. (Gotta avoid any words tainted by a history of -ism or appropriation. Better to second-guess how you say anything, and keep quiet if you can’t think of a surefire way to say it without chafing against any of the many unspoken rules. Language, like many items listed below, has sometimes gone from an important thing to examine to a bludgeon to use as a “gotcha” against people.) (Mel Baggs’ linked posts are quite good.)
• Controlling people’s media consumption. You have to avoid problematic shows and celebrities, or at least earn permission to like them by critiquing all the problematic parts. If you consume the wrong media without sufficient criticism, you corrupt yourself and support wickedness. (Reminds me of fundamentalist forms of cultural critique that say (A) avoid all media with unChristian messages or (B ) it’s okay to enjoy media with unChristian messages if and only if you are really, really careful to recognize them for what they are.)
• Controlling people’s media creation. You are personally encouraging violence against all marginalized people if your story’s characters in marginalized classes aren’t depicted properly. You are responsible for abuse against children if your story features underage characters in a sexual relationship, or if your fanfic ships the wrong people. Your story might possibly influence somebody, somewhere to treat a marginalized person worse (or to abuse a child) and then blood is practically on your hands. (The-real-seebs and their associates have lots of good material scattered around about why this is a bad idea, but I can’t easily find their best material.)
• Controlling what people wear and how they do their hair. (Gotta avoid cultural appropriation. But also avoid all the immense complexity of marginalized people’s debates over what is and isn’t appropriation. Just lay on the shaming and threats of shaming.)
• Controlling people’s thoughts and emotions. You are -ist if you feel uncomfortable with the wrong things, or feel comfortable with the wrong things, or feel an urge to laugh at the wrong jokes, or don’t feel anger at the right things, or don’t feel sad about the right things, or do feel sympathy for people who are too problematic. Or being sexually aroused, or not aroused, by the wrong people or in the wrong way (see two paragraphs down).
• Controlling people’s friendships and relationships. Telling people not to be friends (let alone romantic partners) with anyone who has sufficiently problematic views–at least, unless you are willing to have serious talks to call your friends out on problematic stuff, and end the friendship if they don’t seem to be coming around. (Again, similar to some fundamentalist attitudes on bringing friends to Christ.) (The two links here are to examples of the thing I’m complaining about. I find telling people who to be friends or partners with really fucking invasive and creepy. Behold, a more sensible and respectful approach.)
• Controlling people’s sexuality. Almost all sexual preferences are cool. But sexual preferences regarding race or genitals are racist and transphobic, respectively. You can always say “no”–but you’d better not say no for the wrong reasons. Almost all kinks and porn are fine, but kinks and porn that rely on problematic aliefs or tropes are -ist, and thus shameful. (The four links in this paragraph are to good criticisms of this sort of thing
• Also, some parts of the left can’t decide whether -ism is primarily a structural problem or a personal wrongdoing. The whole discourse around why -ism is bad is built around it being a structural problem. But you can’t effectively judge and control people in your anti-ism movement, or personally blame everyone who disagrees with any idea espoused by your movement, unless -ism is also a personal culpable deliberate wrongdoing, one that corrupts a soul and demands repentance and contrition. Not just an intellectual disagreement or even a non-culpable bias. (Best option: Blame people severely for all their many personal -isms and say it’s just a structural problem and that you’re not blaming them, and that they’re being selfish if they think you’re blaming them.
• Describing people in general so as to vastly overstate how bad they are, in hopes of shocking them into improving themselves (ignoring how it often causes guilt spirals in people who feel accused, and learned helplessness in people who come to think everyone around them is bad)
• Gradually expanding the definition of what counts as -ism (or worse, “being a Nazi”) and gradually amping up the social penalties for -ism (eventually, punching); cf. insecure fundamentalist communities expanding the definition of heresy and amping up penalties for it. (It’s getting worse, as a toxic but perhaps inevitable SJ response to the disaster of Trump’s election. It is the opposite of the conservative problem of minimizing what counts as -ist to the point of ignoring it.) (Link 1: Alison and others on punching Nazis. Link 2: An interesting but ultimately unpersuasive defense of Nazi punching. Link 3: One of the many reasons it is unpersuasive. Link 4: My own thoughts on punching Nazis.
• Trying to give more institutional power to universities to shut down their problematic speakers or expel problematic students
• Trying to give more institutional power to corporate bosses and companies to fire their problematic employees
• Flat out anti-free-speech rhetoric, or at worst, trying to give more institutional power to governments to shut down -ist (or “-ist”) speech. (An astoundingly shitty SJ response to the problem of conservative trolls who use “free speech” to justify bigotry.)
• The movement is for the benefit of everyone, so the movement is more important than the individual people in it (let alone outside it), so it’s okay to treat people like crap in order to advance the movement. Easily becomes a collectivist, majoritarian, authoritarian approach
• Encouraging people to think certain questions are forbidden to ask or even wonder about. (Do some people’s sexual orientations change over time? Are there any biologically-caused psychological differences in the aggregate between people of different sexes or races? Are wage gap deniers’ statistics really bunk? Shh, asking those questions too loudly would embolden bigots. Also, if you keep asking those questions, it makes you a bigot, because bigots Just Ask Questions too. If you’re not -ist, you’ll know the right answers to these empirical questions without having to wonder about it.)
• They can describe their teachings in as vague and easy-to-misunderstand and sloganizing and jargon-filled a manner as they want. If you find it confusing, it’s not their job to educate you. Go Google it, somehow. (Cf. “Just pray about it and you’ll understand.”) (Mogilevsky on some of the complexities at work here.)
• They can chew you out for disagreeing with them as nastily as they want. If you want to be treated decently, you’re tone-policing. (Mogilevsky on yet more complexities here.)