When writing a formal or professional paper, you need to be prompt, and need to engage the audience in a deliberate manner that shows your expertise. So you really can't be using exclamation points when you are trying to be serious and studious to relay your information to others.
Explanation: When writing a formal or professional text, we need to be the as objective as possible, this applies to the subject, the opinions we gave, the sources we use, and even the language and punctuation that we use. Typically we shouldn't use exclamation points when writing a formal text, because they usually express a lot of emotion which isn't appropriate for a formal or professional writing.
