It is because the IPv6 rollout has not been consistent. Some assign /64 per machine, some assign /64 per data center. Some even go the other way and do a /56 per machine. We've had to build up a list of overrides to do some ranges by /64 and others by /128 because of how they allocate addresses. This creates extra burden on server operators and it's not surprising that some just choose not to deal with it.
It is because the IPv6 rollout has not been consistent. Some assign /64 per machine, some assign /64 per data center. Some even go the other way and do a /56 per machine. We've had to build up a list of overrides to do some ranges by /64 and others by /128 because of how they allocate addresses. This creates extra burden on server operators and it's not surprising that some just choose not to deal with it.