Why is it important that all parties in communication have the "same type of conversation?
Different Purposes Breeds Misunderstanding
People communicate for different reasons and in different ways. There are different kinds of conversations. When two people are communicating for different purposes, or having "different conversations", there's a good possibility that conflict and misunderstanding will occur.
For example, consider a married couple. One person is trying to be reassured that the other person loves him or her, while the other is having a casual conversation without any particular purpose. The person wanting reassurance doesn't get it, not because the other person doesn't love him or her, but simply because it's not obvious that that's what is desired. Meanwhile the person having a casual conversation may perceive the other as too intense. The result? Hurt feelings.
Another example having to do with task oriented versus relationship oriented communication in a work team. George focuses on completing tasks and getting the job done, so most of his talk has to do with the nuts and bolts of solving the problem at hand, while not paying much attention to being polite, or respectful to others.
On the other hand, Bob is more relationship oriented in terms of communication, and wants everyone to be happy or comfortable, and is conciliatory, and tries to involve everyone present in the conversation.
What happens? George feels that Bob doesn't care about getting the job done, and sees Bob as interfering with why the group is interacting or meeting. Bob, however, feels that George is mean-spirited, and doesn't care about the people present. Conflict is an almost inevitable outcome here unless people realize that both are operating in good faith, but simply taking on different roles, or, in effect, having different types of conversations.