Besides the help practitioners will provide to patients, it’s beneficial for them to reply to patients' questions in order to gain visibility. Indeed, the practitioner’s name, specialty, rating and booking call-to-action will be directly visible next to each reply you provided.
Hereby how it looks like:
Doctors who do not propose online appointments but pay for visibility, will not have the "Book an appointment" button but have a clickable link (behind the name) to redirect patients their online profile.