It's probably more like they have DOS support contracted out to some vendor. And when the systems upgraded to the point of not being able to run DOS natively the vendor built this franken-OS to fulfill the contract.
Renegotiating the contract to something sensible like "don't run DOS anymore" was probably hopeless in the face of the bureaucracy, or risked losing to contact.
Renegotiating the contract to something sensible like "don't run DOS anymore" was probably hopeless in the face of the bureaucracy, or risked losing to contact.