In my days of left wing political activism we used to think that the answer was to argue and debate and win people over to our political ideas.
Same story here.
Those debates are why I am no longer left wing, and this is the problem - left wing politics do not stand up to harsh scrutiny and debate, they are grounded in unanswerable fallacy and have absolutely been refuted by history.
This is why the modern left relies on emotional thinking, sloganizing, violent rhetoric, disengaging from and dehumanizing the other side as "scum", and so on. It simply isn't in the interests of some organizations to enter into good faith discussion of politics and expose their ideas to the harsh light of question
Dehumanizing the "other side" and pretending they are "evil", and there is "no point even speaking to them" is a ploy used to stop people speaking to each other and exposing the truth, and it's only bad behaviour and bad ideas that need to hide behind that.