If we brought this attitude into our personal lives, it would make our interactions with family members and colleagues impossible! I disagree with Uncle Bob about X, so therefore it doesn't matter that we have Y in common; I have to condemn him completely. One of my co-workers has a different attitude towards business aspect X than me; therefore, we can't work together on business aspect Y.
Only associating with people whose views are in complete alignment with your own is a good way to become lonely, angry, and ineffective.