“Actually the proper term is Communists.”
True, but they’ll never accept it, and neither will those watching from the sidelines.
It’s curious how people can blot out words that define them perfectly if those labels don’t flatter. “Leftist” puts them within an historical context; if they ask what you mean you can tell them to read up on the French Revolution.
Who knows, maybe they will.
If they won’t we must. We need to brand them with that moniker as it still carries a stigma. Liberal or even socialist absolves them of the stigma as even Marx said socialist was just a polite name for communist.