Let me give an example. Let us say you are a patient and you have a cough and cold. You feel unwell so you make an appointment to see your doctor. The appointment is at 3.30 and you work 10 miles away. This means a round trip of 20 miles (if you are going back to work) and 10 or 15 minutes at least in the doctors office. In the end, he may not treat you except with his expert advice. All this time your workplace has been without you.
Change the scenario. You PHONE the doctor and he asks you questions. He may still wish to see you depending on the situation. However, as in this case, he might simply say you have a cold or you have the flu and give you help, advice and guidance over the phone (with a caveat that you can always be seen if you want to or if you get worse). The saving for the doctor is time (for a consultation that did not need face-to-face consulting) and the saving for you is time and inconvenience. It is a win-win situation which lends itself neatly to consultations for conditions that are thought to be self limiting and which affect people that have a modicum of common sense about them.