You draw the line when you feel that the argument is being presented in bad faith.

I agree that's one way to draw the line, but there's also idiots who argue very stupid things in good faith. And those things often don't deserve deep consideration either, or else you'll spend your life arguing with idiots about nonsense, even if it is in good faith. So there needs to be an additional rule than just the bad faith rule, imo.

You wouldn't believe how many negative connotations I read into your post simply because our messages here are text based.

Oh I totally agree, it happens constantly. I write my messages with the assumption that whatever I write will be misunderstood, if it is possible to misunderstand. Then I try to word things in a way to avoid any misunderstandings. Even just using the wrong phrase can trigger an emotional reaction in people that then closes them off to logic. And this mechanism just feeds tribalism, like you said.