thats observably not the case: countries where the government is unopposed in speech censorship do it pretty well. the only way people can engage in speech banned by the authorities is to do so on platforms run by countries who dont care about what they want to say

Subversive speech can survive despite the efforts of a government. Foreign platforms are one option, another is posters put up at night or materials circulated hand-to-hand.

But it's true that it's going to be a lot easier to remain anonymous when your opponents don't have the resources of a government.