The primary means western propaganda uses is to persuade. It has to be persuasive because the targets can choose whether they believe it or not. Nobody has to comply, and dissenting voices and alternative narratives are available. Also it competes in a market for ideas and so there's a degree of selective pressure to improve so you're quite right it has become quite sophisticated whereas authoritarian propaganda can rely on excluding dissenting voices.

Soviet and Chinese propaganda, at least the types you're taking about, persuade by projecting power. It's about psychological domination, with heroic poses and strong simple messages emphasising the inevitability and necessity of party control. It's blunt design is part of the point. Thousands of gymnasts and marchers in perfect lockstep. Zero individuality. It doesn't matter if you are persuaded, as long as you get the message that you have no choice but to comply, and look, everyone else is complying!

Take the poisoning of Navalny. They don't need to persuade anybody in Russia that the state didn't do it. Everybody knows the state did it, even those that are pro-state. The point is to send the message, this is what will happen to you if you push us too far.