This is very perceptive. Attempts at honest discussion often seem to be derailed in exactly this way. Discussion of the actual issue is avoided by loud assertions that take a lot of time to refute. Which "side" derails it does seem to depend on who the "weak man" would hurt.
Just don’t participate once the conversation gets derailed. Learn to exit gracefully, and usually if you did make a point addressing the complexity, likely someone got something out of it.
Surround yourself with people who disagree with you, but are good at it.
I would say bring back empiricism as a big component of knowing if something is true, or at least before you discuss it as something that is right.
People are aligning with complex theories with no underlying basis, other than their feelings and utopian visions, and then getting emotional about it.
Is there any way to avoid this?