Have you ever burnt yourself or smashed your finger and then lashed out at someone immediately after over the littlest thing?
All of us here are in pain or distressed almost always even if were not aware of it. This makes us more sensitive and on guard and when people disagree with us, we can take it personally and then it escalates from there and you get this us/them dynamic. You see this everywhere, not just here.
If you realize this you can be more empathetic to people even when they aggravate you because generally everyone's original intention is the same (to get better and help other's get better) even if they don't go about it the best way. Easier said than done I know!