What is the rationale behind requiring a meeting before filing academic misconduct charges? Some universities have a rule that, for example, "if it appears that a student in your class may be guilty of academic misconduct, you must promptly ask the student to meet with you informally to discuss your concerns."  The quote is taken from one such university, the University of Wisconsin.  UW's Academic Misconduct Guide for Instructors goes on to say: "You can discuss the matter with the student in person, by telephone, or online. During this meeting, you should explain why you believe the student may have committed academic misconduct and give the student an opportunity to respond. It is not necessary to inform the student in writing before this meeting."

What is the rationale behind this type of requirement?

Bonus: How common is this?  When did universities in the US start instituting this type of requirement?
I believe that the main impetus for a meeting with the student is to inform them directly that they are being charged with academic misconduct, and to know that they are consciously aware of such charges, so that they cannot claim "no one told me." In general, until recently, at my school, the process dragged on and on because the students need to sign a form indicating their willingness to accept or refuse the sanctions. 

However, in recent years, this process has become more digital, and, for instance, at my university, the school no longer requires a face-to-face meeting. The forms are filed and processed electronically, and notification of the intent to file charges can be provided to the student via the campus email system.