Yeah, a state that is constantly in war(s), paints the target countries du jour as the enemy building racism against their citizens, tolerates torture and police shootings (letting officers that do that shit free), and is obsessed with violence and gun ownership, suddenly is worried about "spreading extremism".
In light of this, worse than band-aids like "let's close the internet forums they frequent" is the new blaming heavy metal and computer games for mass shootings...
It is entirely possible for one fraction of the population to be concerned about spreading extremism while another fraction does as you describe.
If you assume that the people of a nation stand in line behind those in charge, you will be continually surprised.
What about Stalin?
What about non-white supremacist manifestos? They do exist, you know.
How much history would you erase due to your belief that words are capable of 'infecting' (presumably) lesser minds?
There's no evidence that manifestos spread "extremism and terrorism like a virus". Words are not able to infect people against their will. There are only ideas, and they can only be fought with reflection, more words and more ideas.
In the end, white supremacists and other kinds of supremacists existed before the internet. By supporting China-style censorship you're not actually eliminating those ideas, or even stopping their spread.
They existed before the internet, but the internet has given them a tool to organize that they didn't have before. And by censoring them online effectively, you take this tool away from them.
Which is exactly what happens in China. I am sure Chinese officials know ideas and philosophies spread on the mainland, but as long as the people who believe in those ideas and philosophies can't organize effectively then they can be controlled.
Edit: in a less sarcastic way, a government can accomplish quite a bit if it has no concern for the rights of its citizens. There is a reason we don't do this kind of thing in the West; it's a good reason and it's one that China will eventually learn the hard way.
That's exactly what China does, for their definition of extremist.
But, of course, that could never happen in the US, right? I mean, it's about as likely as a bombastic demagogue being elected to the presidency. /s
... are you kidding?
As an aside, I've defended certain versions of democratic socialism (though I'm not a fan of it) to some of my friends that are recent immigrants from China (having worked grown up there and worked in the corporate world). All of them think capitalism and Western democracy is the greatest thing since sliced bread.
It might make the tiniest bit of sense if we were collectively able to do something preventative about mass murders before they happened by using that “insight”. That certainly does not seem to be happening.
No, I think the time is coming where white supremacist manifestos and the like should be actively stamped out by society.