1. People are often not, in fact, arguing in good faith. It's easier to see this if we look at things in hindsight, though sometimes it's super obvious even in the present. One could look at Russian state media on Ukraine as an example where trying to take their arguments at face value would have you contorting yourself into knots. This takes you further from reality, further from the truth.
2. There are often good points to be made on exactly where your opponent is weak. That they're weak on some point isn't a reason to shy away -- if the end goal is more knowledge and understanding for all, then ignoring certain aspects of an issue just because you're trying to be "nice" is a net negative.
To use #2 against myself: I'm generally pro multi-modal transportation, but it's true that car dominance has some advantages for larger families, and that the 'transition period' where you're taking away car resources but transit/walking/biking still aren't all that great is awkward. Someone arguing against my points should not just ignore these areas because they're areas of weakness for me. They're things people deserve to know about, issues that would have to be handled.