From The Professional Product Owner book: Growth of technical debt by poorly designed software where budget is progressively consumed as the old software is kept alive. If you fail to address technical debt now, you will end up paying more interest in the future.
Netscape’s project to improve HTML layout in Navigator 4 has been cited as an example of a failed rewrite. The code base was so bad that developers couldn’t work on it anymore; they decided to rewrite a new engine, causing many failures in existing features and a delay in the release of several months. Meanwhile, Microsoft used incremental improvements to Internet Explorer and overcame those obstacles.
The Professional Product Owner book