I think there is a disconnect between people in different communities because reasonable people naturally avoid the places where extremists congregate, so you only encounter them if you either venture into their den (which reasonable people rarely have any incentive to do) or you become one of their targets. If neither of those describes you, you may scarcely be aware of their existence.

This also explains why both sides commonly feel victimized. Each only sees reasonable people on their side and not vicious extremists because they don't hang out with the vicious extremists and the extremists on their side are out victimizing the other side and not them. But they can see the extremists on the other side when they come to attack.