Something for people to keep in mind: Identitarianism is at least partially independent from the other political axes of economic conservativsm/liberalism, social conservatism/liberalism, and authoritarianism/anti-authoritarianism.
It seems to me that there are identitarian and non-identatarian versions of most clusters of political views. For instance, the difference between a strong liberal and a typical "SJW" is mostly whether or not they're into identity politics. I'm very liberal, and on policy stuff, I agree with most SJWs pretty much across the board.
Hillary's presidential campaigns in '08 and '12 pushed the gender identitarianism angle really hard, but Hillary herself is a neoliberal, centrist on economic issues and lagging on social issues by about a decade.
TERFs are strongly identitarian but are rejected by the rest of the identitarian left because they aren't sufficiently liberal socially.
Libertarians tend to reject identitarianism, but there are certainly identitarian libertarians, as evidenced by Ron Paul's connections to the KKK (receiving donations, having articles written for their magazines under his name, etc). Even if he is to be believed about rejecting the KKK, the KKK certainly didn't reject him.
And so on. Point is, it's not always wise to assume that someone has a particular set of political views because they're identitarian, or assume that they're identitarian because they have a particular set of political views.
It also very often comes hand-in-hand with extremism. Identitarianism almost always implies some sort of struggle between identities. Any time you have a struggle between identities - especially identities based on immutable birth-controlled features - the identitarians are inevitably going to continuously inflame the conflict and create vicious cycles. Hence Richard Spencer's "we're identity politics for white people". And the more it happens, the more identitarian people become, even if they weren't previously. "Hey, I'm [X], I have no control over being [X], you're saying that I'm [not good in some way], and I know that's not true about me and people I know. Why are you doing this?"
It easily lends itself to conflict theory thinking, and black-and-white thinking, and feeling victimized or offended. (The latter is definitely true of staunch right-wing identitarians as well; I saw a lot of comments from alt-right people who were upset and offended over some jokes involving white people that Dave Chappelle made in his last special, for example, while completely overlooking all the jokes he made and has previously made about pretty much every kind of person.)
I suspect it's also more likely to attract certain personality types which are correlated with... being shitty people, I guess. For example, external locus of control: "the bad things that I perceive to be happening to me are more due to my identity than my actions and decisions".
And people who feel little purpose, meaning, or sense of accomplishment in life can use their identity as an easy escape hatch. It's one ever-available way to fill that deep void. They can cling onto the achievements of their long-dead, very distant relatives, and "enlist" in the "army" of their identity demographic. They can make themselves feel powerful and goal-driven by in some way "fighting for" their identity. They feel like they're contributing to something much larger and more important than themselves. They can do this and feel very driven and purposeful even if they don't have any skills or much intelligence. For someone with no skills and low intelligence, that may even be one of the only ways they can ever consistently feel that way. Most humans desire things like this at a visceral level, and it's no surprise that people who otherwise can't achieve it will fall into it, much like how it's no surprise that people who can't easily find sexual partners (another visceral human desire) will go the easy route of constantly gorging themselves with porn. Identitarianism is purpose-porn.
Despite all that, some degree of it is also perfectly understandable or even necessary in some circumstances. That makes it even more dangerous. Like I wrote above, the actions of identitarians may lead you to become an identitarian even if you weren't previously, and even if you actually are intelligent, wise, productive, successful, and mature.
For example, how could you be a Jew in Nazi Germany and not be an identitarian in at least some way? Or a black person under Jim Crow. Or a Catholic in 16th century England. And for the current era, if you happen to be white and happen to become exposed to a lot of content with weird, highly generalized, accusatory and demeaning ideological language towards white people, you're probably going to become at least 0.1% more identitarian than you were before, whether or not you're aware of it or want to, and perhaps even if you are generally a tolerant, inclusive progressive person yourself.
It's a very slippery slope that can easily lead to distorted views of just how much negative sentiment concerning your identity is out there and how serious it is, with a resulting disproportionate reaction. Humans have a lot of biases, and if people in your bubble regularly aggregate compilations of things like this, your threat detection instincts may cause you to take a war-like posture that's more defensive than the true reality of the situation calls for. It all feeds into the cycle, because that may also be exactly the same process that caused the writers/speakers of said ideological content to become the way they are in the first place, and your own transformation may then create more of said people, who then may create more people like you, etc.