Most rail accidents are the results of several factors and if any of those factors hadn't been present the accident would not have happened. The fact these accidents required both the track and the vehicle to be out of spec means that you can't really say that one defect caused the accident more than the other.
For example a defective AWS doesn't in itself cause an accident, since some kind of driver error must also happen, but few people would disagree these days that sending a train out with no working AWS is a failure of maintenance.
The difference being that a train would not be allowed out now a days with defective AWS.