This is false sense of security. Industrial SCADA and CAN networks have been found full of vulnerabilities because people assumed they were magically secure by

This is false sense of security. Industrial SCADA and CAN networks have been found full of vulnerabilities because people assumed they were magically secure by simply not using IP. You can easily isolate an IP network and inspect its traffic. You cannot easily inspect less common protocols. Obscurity and lack of tools never helps security.