Remember, server technology means there is not one single computer handling every aspect of Disney's applications. Functions are distributed across a vast number of servers in multiple locations. Some functions will have failover backups, others will not. In the event of a communication outage, i.e. an ISP has a major disruption, parts of the system may not be able to communicate with others, while other parts are just fine. Where you are located often plays a part as well, as there will be multiple paths that hit different mirrored servers all across the world.
How these type of outages manifest themselves in any particular case is always something of an unknown.
Steve