I propose that most of the code written in the old days, in COBOL in particular, was not done by computer scientists. There were many lanes for learning COBOL, and they included community colleges and industry training courses. The amount of "computer science / software engineering" concepts that were widely known (or even possible) in those days was very limited. 're-engineering' the code is a valid operation, but the amount of code is extreme. and without a deep testing regime, a dangerous journey. so, we keep on keeping on. the same way.