This is my interpretation. Usually bad devs I've worked with will mistakenly keep things DRY by reusing code in a bad way, for example modifying existing classe

This is my interpretation. Usually bad devs I've worked with will mistakenly keep things DRY by reusing code in a bad way, for example modifying existing classes to handle cases they were not meant to handle. The most primitive example is reusing a function because it does 80% of some logic and then adding some bool flags to make it do something a bit different. Instead one should always abstract things and extract reusable bits, but only if it makes sense. But more often than not, lazy or misguided devs will see a similar piece of code and try to reuse it by modifying it to add new behavior, because "copy/pasting is bad".