Can work, yes. Has the budget (in both money and engineer time), probably not. It’s not as easy as just installing a new appliance and flipping a switch, especially for companies with low risk appetite and strict SLAs around service uptime.

Plenty of enterprises have mission-critical applications running on mainframes because either no one understands the software enough to move it to more modern platforms or because the business can’t spare the time/money to have their engineers work on moving it. It’s hard to expect them to adopt zero-trust and BeyondCorp with that kind of culture.

I agree “don’t trust the network” and especially the idea that those four walls don’t offer any real protection, but enterprise culture is incredibly slow, inefficient, and risk averse.