I think you underestimate the scope and scale of systems like this. And maybe overestimate the success rate of rewrites, made worse when the developers have no domain experience and a rushed schedule. Under the best conditions rewrites fail more often than not.
Maintaining legacy code isn’t always easy, but it has a big advantage over a rewrite: it works and satisfies requirements to some non-zero percentage, whereas imaginary code built with “modern tooling” does not work or meet any requirements. COBOL and old business systems aren’t that hard to understand.
Maintaining legacy code isn’t always easy, but it has a big advantage over a rewrite: it works and satisfies requirements to some non-zero percentage, whereas imaginary code built with “modern tooling” does not work or meet any requirements. COBOL and old business systems aren’t that hard to understand.