I have always believed what the article more or less states. But you have to remember, the primary and maybe only source of duplication in software is situational dependency (the other word escapes me for this). If there was a universal tree of software functions that could be accessed over a network no function would ever be duplicated and every function would be reused from a central tree. When you put 2+2 inside a method or function body you just duplicated code. or any code inside a method or function body.

This is why we have to have programs that duplicate code by doing anything like adding two numbers together or complex logic that is easy to create bugs when someone wrote it 40 years ago better. Because code reuse is mostly done on a very small scale.

Given thats the case when you start on a new React project as an example you are not reusing application code you are duplicating the react framework so you can duplicate every other web app in every sense except maybe the visual.

There is no such thing as full reuse and until we get to a universal network invocable function tree that can be extended only when its truly unique we never will. Maybe AI will do this. People cannot.

At the end of the day code duplication needs to exist to optimize for local correctness (or incorrectness) and speed and abstractions goal is not to provide pure reuse. Its to provide a place to "put your logic" that may be similar and has access to typical state that some kind of widget might typically need.