(As an aside, the legality and ubiquitous acceptance of pornography and the illegality of sex work is a weird inconsistency in modern culture that I really don’t understand.)
Free speech protections in the US are pretty strong, but I’d suspect the harassment from that farms site is probably illegal.
Credit card processors are within their right to refuse to support white supremacy content (which I think is reasonable). BTC enabling these people isn’t great, but it also enables people in situations where it’s the government that’s objectionable (someone taking money for a blog about banned topics in China or Saudi for example).
In many hostile countries just getting your money out without it being taken by bad actors can be hard.
This resilience is a strength of BTC which can be used for good or evil. It’s also clearly an existing use case of the blockchain.
"Its CEO, Carl Ferrer, pleaded guilty to charges of facilitating prostitution and money laundering, acknowledging that "the great majority” of the adult advertisements on Backpage were actually advertisements for prostitution."
So there seems to be admission that the site's main purpose was prostitution and money laundering, whether or not the other accusations are true.
As for the other sites, I don't know the intricacies of US law, but "it's technically not illegal" is usually a bad way to make a case. Those are communities dedicated to cyberbullying, extreme-right wing views and white supremacy. All those things are documented to have cost lives and in many countries are either already illegal or close to becoming that.
In any case, those are not the noble dissidents in authoritarian countries that Blockchain advocates usually argue with.