Why? What situations do you need a doctor to use a synchronous, interrupting, unscheduled communication medium for, where the situation is not serious enough for you to already be in the hospital?

My doctors can communicate asynchronously through the MyChart app/website (the app is fairly terrible, I would rather them just use email, but oh well) where I can read and respond when it makes sense for me. Any test that they are running where the results could be bad is already asynchronous (or I am in the hospital) so delaying a few hours in reading it doesn't seem like a big deal even if it is something bad.