Your customers can't take your product more often than once or twice a year. Because the product doesn't need to leave the building, the teams don't release internally. Nor do the teams demo on a regular basis. The teams miss the feedback loops so critical for an Agile approach. Their Agile transformation falls apart.
Rethink Your Definition of Customer
What if we expanded our thinking of "customer"? What if we thought of all these people as customers: