It's polite to confirm an appointment.
Fred has scheduled an appointment with a realtor, three months ago, and he was now preparing to head over to the realty office.
Fred wants to attend the scheduled meeting.
Fred calls the realtor, the week before the scheduled meeting, to remind them of the specific business that he intends to conduct.
Fred prepares the appropriate documents for the business he wants to conduct and drives over to the realty office.
The realtor is able to update Fred on the subject matter and is able to prepare, appropriately for the meeting.
The realtor does not remember the conversation that they had with Fred, and they are not prepared for the meeting, so they both feel awkward and unprofessional.