The sheer age of those COBOL systems is, oddly, actually something that works in their favor. Because they’re old, they have been relentlessly debugged. When a program is first written, it inevitably has problems…But those COBOL programs that run the world? They’ve had decades for coders and users to uncover all the problems, and to fix them…They’ve been debugged more than just about any code on the planet. This idea — that older code can not only be good, but in crucial ways superior to newer code — is at odds with a lot of Silicon Valley myth making.
Legacy == Proven.
Clive Thompson on the enduring fitness and necessity of COBOL https://www.wealthsimple.com/en-ca/magazine/cobol-controls-your-money