MOR,
You are way off the mark. The Ground Controller is responsible for assisting in preventing collisions between aircraft moving on the apron and manoeuvring area, whether Surface Movement Radar is available or not. A clearance to proceed along a taxiway does not imply that there is sufficient room for aircraft to safely pass each other. The ultimate responsibility for avoiding ground collisions must always belong to the pilot. How can Controllers situated several hundred metres away be expected to judge safe wingtip clearances? Max Angle is spot on.