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.

... 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.