[kazagistar]

The purpose of many opinions is to gather support for some kind of sociopolitical state, and changes or maintenence of the political status quo cause harm or maintain harm respectively. For example, if I lived in 1800 and stated the opinion that "black people deserve equal rights", it would be dangerous to and greatly financially threatening to southern landowners. The added effect of these opinions would be proven out by history. And while that opinion would turn out to help far more then it harms, other opinions like "jews undermined our army in the great war" would turn out disastrous. I would say that opinions are some of the greatest powers in the world, and calling them harmless is dishonest.