Unfortunately, people who are warm, friendly, understanding, and capable of grasping that they can be wrong are few and far between. Especially on the internet.
Also, being able to grasp that you can be wrong won't necessarily protect you from the backfire effect. For example, I'm capable of grasping that I can be wrong, but I don't want to be wrong. I really, really, really hate losing. So if you throw more contradictory evidence my way, it'll only increase my desperation of trying to prove that I'm not wrong. That's the backfire effect right there.
The only people who aren't as susceptible to the backfire effect are the ones who don't care as much about losing. And those are even rarer.