The big issue here is that a client server model has an inherent trust on the network to be 100% there when you need it. Cable modems or DSL (probably) fail at a much higher rate per day intermittently than a fleet of 2,000 sets of redundant computers.

Consider - how would you handle order taking if the network dropped?

A buddy did IT for a theater for a while - they had a similar problem where they’d lose access to their payment processor regularly. No one ever noticed since the system queued ops locally until the network came back up.