Why is it important to use an academic voice rather than a conversational voice in research papers.

1) Why is it important to use an academic voice rather than a conversational voice in research papers.2) What constitutes plagiarism and why is it considered the felony of academic writing?Use APA 7 formatting.It is an opinion essay
It needs to be aroun 450-500 words.Please use at least one reference (can be the text book or some other reference).