Irrelevance as a vice, is a lack of intellectual importance or influence, while Impotence as a vice is a lack of emotional importance or influence. That which is a full, complete communication will usually have both intellectual and emotional aspects to the communication. Otherwise we aren't talking about a communication. We are talking about either facts, or emotional venting or expression.
Full communication needs both emotions and ideas.
Irrelevance and its twin, Impotence (socially) are then two forms of the vice of deficit of the virtue of Influence.
We need influence in social groups in order to get the group collaboration and support toward our goals.