Comment by munificent

> Conversely, fixing duplication is never hard. Just move the duplicated code into a function.

I think the single biggest factor determining the difficulty of a code change is the size of the codebase. Codebases with a lot of duplication are larger, and the scale itself makes them harder to deal with. You may not even realize when duplication exists because it may be spread throughout the code. It may be difficult to tell which code is a duplicate, which is different for arbitrary reasons, and which is different in subtle but important ways.

Once you get to a huge sprawl of code that has a ton of mostly-pointless repetition, it is a nightmare to tame it. I would much rather be handed a smaller but more intertwined codebase that only says something once.