It may work in local elections but nation wide elections require the popular mandate. Humans like to believe that they have a stake in the system, however small.
The general public get to know their national candidates first at the local and then state level, and those candidates are judged as "better than a head of lettuce" by their peers in office.
The political wing of government is essentially (ideally) just about debating policy - it's the civil service, military, and judicial wings that get tasked with making things happen (subject to checks and balances).