Because I have so many health issues, all my doctors are through Kansas University Health System. They use MyChart. I can send a message to any of them, and if they want to consult with another one they can both see the entire conversation and both can then respond to me.
I can review notes from visits in case I have forgotten just what was said.
I can pre,check in, and not have to spend 20-30 minutes filling out paperwork, before I can see the doctor.
I also have a 22 yo autistic son, and they know to contact me through his MyChart.