I think there are many cases where it was the tech workers themselves who argued for isolation from the customer so that they may focus harder on whatever tasks. I used to be one of these workers. I argued very hard for it. I regret that today.

On the surface it seems rational, but it quickly turns into a system of perverse incentives because now the development team must maintain an illusion that they are constantly overwhelmed with tasks and could never hope to spare a microsecond to assist the customer. This misalignment is how you wind up building your own web frameworks and databases from scratch. It turns into a self serving monster that eventually dominates the entire business. From the perspective of the business, many of these development teams look like they're behind some modern day iron curtain.