Incrementally fixing the &quot;crappy&quot; codebase is great in some cases: Michael Feathers&#x27;s book on rescuing legacy code is fantastic. However, the limit comes at the language barrier.<p>Consider a COBOL codebase on a mainframe where you cannot find developers interested in learning the language and developing against the mainframe is convoluted -- you may not be able to pay talented people enough to toil in those coal mines, and you have to have to overpay subpar talent (or chase after the handful of expert mainframe COBOL developers.)