>Half of the forums are constantly bombarded by anti-black, anti-asian and anti-jewish racism. These posts do not get removed.

Depends on your definition of racism, but when someone talks about "glowniggers" that that nothing to do with race, other than appropriating for themselves an offensive word that might be considered racist (depending on who uses it, I guess?) in other contexts.

Same thing when something about jews in the context of large corporations comes up. Nvidia is a popular target for their exploitative practices of "jewish tricks", yet the CEO in charge is about as far from jewish at it gets. It's more about repurposing the greedy banker stereotype than pointing out any concrete connection to some racial background and some hatred for it.

The point isn't to express hatred for some group of people based on their genetics or other factors, but to be at offensive and repulsive as possible on purpose. There are multiple reasons regulars like it that way, among them that it allows for creative and free expression, to keep outsiders, or "normalfags" (again, this isn't about sexual orientation at all, even though it's an insult) away who don't fit the culture well and because it can be funny if done right in the same way any other offensive language can be funny, especially the more over the top ridiculous it gets.

Of course, there are also posts that contain truly racist statements and other bigotry, but most of that is on /pol/, which the other boards hate for its unsalvagable stupidity it attracts and spreads everywhere else. How many of those posts are serious is also hard to say because trolling is a sport, more or less depending on the board. Interesting fact is that, if offline meetings are representative, most of /pol/'s users aren't even white males as the stereotype might suggest. Mostly males for sure, but the majority looks hispanic/latino and asian.

You might disagree and claim that the way language is used is unabiguously racist, homophobic or whatever because the words are, according to the mainstream definition, but that's not what most of them mean or how they're used and perceived within that culture. How do you even know it's not a gay person calling you a faggot? You think there are no gay, jewish, black or whatever people on 4chan? Likewise, often something that looks like an insult is counterintuitively actually the opposite. Like when you banter with frieds and you call each other assholes without meaning it.

If you can't get over that, it's fine, but I think it's unfair to judge a subculture based on language without taking into account how it's understood within that culture. Or if someon makes and posts a gif about Hitler doing that cat dance it's not expressing a hatred towards jews and the desire to exterminate them. It's funny because it combines something horrible with something utterly innocent in a ridiculous way and you just know how some would totally get angry over it and lose this shit, so it can be funny just imagining the reaction.

Call it juvenile, bad taste or trolling at worst, but for the most part it's not about unconditional hate based on some criteria that the word or image suggests at first. Sometimes it is (how do you even know for sure) and it's easy to tell when something is at least meant to be perceived as actual hate speech, but I don't mind learning a bit about how those people think and why they do it, so as long as it's not the majority of the content I can deal with it. Hatred exists, no way around it, but that's a different discuss. If political at all, the closest way to describe it would be as anarchy.