Every conversation has a limited bandwidth, and the participants usually have a shared understanding—an agenda—of what topics constitute an appropriate use of that bandwidth.  When you say something that goes beyond that agenda, <i>even if what you say is true</i>, you risk annoying the other participants, not just because you’re injecting noise into the communications channel, but because you’re asserting a right to change the agenda of the conversation.  If you do this often enough, they are more likely to come away with the impression that you’re arrogant and rude than remember your corrections to their false understandings of the world.