I’ve just had a barrage of comments trying to rip me apart for suggesting that a political opponent’s position should be understood

Ironically, I've never understood the mindset of those commenters. How can you argue against something, or even know if you should argue against it, without knowing what "it" even is?

I generally go a step further than believing that every argument should be understood, and say that every argument should be considered as well. You shouldn't reject an argument purely because it gives you bad vibes. If it's obviously wrong, it should be obvious why it's wrong. In practice you don't always have time to engage with someone promoting obviously dumb ideas, but you should at least yourself know why you consider them to be wrong. I call this "radical possibilism" because you always consider the possibility that an argument is correct.