Hi Gatsby,
Main reson is cost/benefit balance.
I observed in Turkey that generally surgeons do not make hair transplant themselves, they provide initial consultation and control afterwards. There are few clinics in which surgeons themselves make hair transplant, but they were extremely expensive for me.
I visited 4 clinics before deciding. I tried to judge experience of technical staff rather than name of surgeon giving his-her name to clinic.
Still i would suggest someone to have a doctor surgeon hairtransplant if there is no budget concern, unfortunately which I could not efford.