We really don't.
> What I find the weirdest, as a foreign outlooker is how it’s defended.
As a foreigner, what makes you think you know what america is really like? Just because of the nonsense you see on the news?
> Nobody had any problems with ISIS getting censored off the internet
I did and many americans did. I don't believe in censorship. The easiest way to combat extremism is to show it.
> but these right-wing nut jobs somehow have a right to spread their equally harmful propaganda?
If it is harmful, isn't it better to discuss it? To put it out in the open?
> I don’t get it.
My advice is to take a class in philosophy, history and educate yourself. People who think like you are why nazi germany and the soviet union existed.
"Harmful propaganda" is the excuse every authoritarian uses to enslave their people. "Harmful propaganda" is itself harmful propaganda.
How do the saudis silence lgbt? By saying it is harmful propaganda. How do the chinese silence religion? By saying it's harmful propaganda. How do the russians silence democratic advocates? By saying it is harmful propaganda.
If there is harmful propaganda, then lets bring it to light and expose it. Only sneaky authoritarians with ulterior motives use "harmful propaganda" as an excuse to curtail people's rights.
A vegan shot up youtube a few months ago. Is veganism harmful propaganda? Should we ban all vegan content? Of course not.
Funnily enough, you have so much in common with the right-wingers you claim to hate. They hate "harmful propaganda too" and want it censored.