Have a digital frequency for routine communication: like authorization to taxi, take off, clearances, flight plans, pattern requests, confirmations, and traffic. Keep an analog frequency for communicating through emergencies (kind of like Guard).
Sometimes dangerous situations are averted by pilots realising the controller had made an error, like clearing a plane to cross a runway while another is taking off [0]
This kind of thing might be much harder to catch if clearances are given in text, or even impossible if they are routed only to the specific aircraft.