The weird thing is, the nature of their business does not imply any significant computing needs. As a rough estimate they have served on the order of 1 billion

The weird thing is, the nature of their business does not imply any significant computing needs. As a rough estimate they have served on the order of 1 billion customers, so that suggest they need 1 billion, multiplied by some factor of cruft, database rows. Depending on the cruft factor that should be somewhere between easily fitting on a single disk, up to a few of them. Add in redundancy and backup and we have still not filled a rack cabinet. Maybe all those computers are doing something that someone thought was important, but it is not serving the core business.