Caliper brakes and cantis were designed for different purposes. In road racing when cycling in groups the need is for modulation in braking so as to respond immediately and proportionally to changes in position within the group. In that safety is the issue her , modulation of braking, not raw power is the priority.
In heavy touring, when carrying heavy loads, or in extreme conditions when mountain biking, sufficient power is needed to cope with this. The configuration of cantis and of V brakes can deal with these conditions.