Digging my heels in and shaming my callous opponent won't help, and feeds into the myth of the "holier than thou" leftist. You might genuinely believe you're a better person, but unlike someone who is right-wing individualistic, it won't make you happier. The ultimate goal is to agree, not to win at moral point-scoring.
If we cannot love our enemies, because they are busy trying to take us down, does that make us worse at being Left? It's complicated.
Is it closed minded to reject bad ideas and disingenuous arguments? Is there really any merit in sickening and hateful rhetoric that reduces lived experiences and historical legacies to "whiny snowflakes"?