> I see no way to have a cohesive, official censorship apparatus with centralized control, unless the method employed simply involves cutting cables. That would be pretty unambiguous.

Social control and censorship is far more effective than governmental censorship. Being "excommunicated" or ostracized from your social group is enough to prohibit many people from making political expressions (or otherwise).

For a dumb but illustrative example, think about how your posting habits on social media might change if your relatives were receiving those posts.

The best part is that it allows the government to indirectly encourage practices and behavior that would likely receive criticism in the global community if done directly.