My limited understanding is that under certain weather conditions the pilot given his experience and ability to interpret the conditions is always going to be better at maintaining the approach than an autopilot
This was true on older types (B707 being one example), however, this all changed when two different types emerged...the HS.121 Trident and the L1011 TriStar.
These two were the first truly successful narrow and wide-body types respectively to operate to CATIII conditions, without restriction.
Ah, Lockheed, superb....just ask the pilot that flies one