It is said that there is a difference between talking to someone and talking at someone. I think that this might be one aspect as to why interpersonal aspects of communication steeped in the realm of interactivity would be more relevant and appropriate. Involving individuals in communication and finding ways to bring them in can represent ways in which discussions can come alive and be more vibrant, revealing more to be gained. When one engages in a static form of communication that simply talks over or at people, there is less of a chance to retain information and engage in dialogue between multiple people that validates their voices and experiences. Interpersonal communication is more active because it involves more people, and helps to authenticate their own voice in the dialogue. It is in this realm where good and relevant communication is appropriate and lives. If you think of your best conversations, they were probably ones where you were heard, where your voice was substantiated, and where you felt a certain relevancy to the conversation
I am resisting the temptation to edit the question to make it more meaningful. I think it would be more enlightening to leave the question as it is, and examine some of its implication.
To begin with please note that all communication are always interpersonal communication. For any communication to take place there must be at least two persons participating in the process. This makes all communication interpersonal.
Secondly, all communications are dynamic. This is what makes a communication so difficult. Processes involved in formulating a message to be communicated, and receiving and interpreting the messages received is very quick and complex. This speed and complexity makes all communication a very dynamic process.
Further relevance of communication refers to the subject matter of the communication irrespective of the communication process. The subject matter in a specific communication can be relevant or irrelevant irrespective of the effectiveness or ineffectiveness of the communication process used. When the situation demands that information be provided on performance of a person, but the concerned person only talks about his capabilities rather than results produced, then he is talking about irrelevant things irrespective of how impressive his talk is.
The essential characteristics of an effective communication process is that the what is intended to be communicated by one party is received and understood completely and correctly by the other party. One of the ways of improving this kind of understanding is to pay attention to talking as well as listening.