This is extremely true, and people on the right simply do not understand the fundamental issue.

"Principled Leftists" are simply Useful Idiots that the Left will march into machine guns.

Leftists are only concerned with power, their establishment of principles (as far as they are concerned) can only be done once they've achieved total victory. And all actions are justified in getting to utopia.

This is why no one has murdered more Communists than Communists, and why Leftists invented a term for actually doing the shit they believe in on occasion: "praxis"