First off, it's not practical to ban all speech supporting censorship, because then all speech supporting that specific policy (including your own comment) would also have to be banned.
I'm not aware of other countries suppressing speech that is intended to censor others, though I am aware that countries like France criminally censor anti-semitic remarks such as holocaust denial. Is this what you mean? I've never heard of the rationale behind that censorship being that that speech is intended to silence others.
In any case, I do think there should be a near-absolute right to speech for three reasons. The first is a slippery slope argument -- any time you criminalize behavior that is open to human interpretation, the power of that interpretation can and will be abused. The risk of censorship is too great to put in the hands of regulators or politicians, even with n degrees of "oversight".
Speech also cannot cause direct harm, and censoring does cause harm in that it takes away someone's right. For that reason, it seems reasonable to censor speech that actually cause harm to happen, though idle threats or general instructions do not qualify.
Lastly, banning speech does not allow the ideas it represents to be addressed in a serious manner, meaning that proponents of that speech will always (likely somewhat correctly) be able to claim said speech was banned in order to enable attacks son that sort of speech. This goes hand-in-hand with the idea that eventually whatever speech that would be banned would just be defeated in the marketplace of ideas, and banning speech just prevents it from being struck down as irresponsible on even ground. I think this can be evidenced by their being no more serious a problem with holocaust denial in the United States than elsewhere in the west where it is banned.
As you can probably tell, my opinions fall very close to the Supreme Court's interpretatin of the first amendment, so I guess I am a bit biased in my opinion.
Can it not? It can be used to humiliate people to the point of suicide. It can be used to target someone for violence. In the case of people with photosensitive epilepsy, particular visuals could kill them.
Even if the harm in some of these is “indirect”, it's not less problematic.
This is something that countries differ on. The US's notion of near-absolute free speech is rather unusual.