You’re right that it’s ineffective, but the messaging and emotional hooks are powerful. “The left” at its core challenges the ego. It sees society, culture, economics, politics, etc and says “Do better”, or if we’re being pleasant “We can do better, let’s build it”
“The right” tells your id what it wants to hear. Everything is as it ought to be, you don’t need to improve yourself, this is the best place to be, failures are because of ‘our enemies’.
“You’re fine, it’s their fault” is a very easy pill to swallow, and the mental gymnastics start quietly