You are confusing content for expression/listening. It’s like confusing a computer for electricity. That or you are merely misusing the word purpose.

If you want to be better at interpersonal communication you need to be excellent at listening. Empaths find this comes naturally but people with learning disabilities and/or autism will find this impossibly challenging while perhaps convincing themselves of self-mastery.

Listening and expression come in three dimensions: verbal (the words), vocal (use of voice), and physical (the rest of the body). You need to pay attention to all three. Dishonesty is when those three are in conflict. Most people are not good at this and have no idea just how bad they are at it.