These kinds of abstract code discussions almost become immediately absurd because, for it to work, we have to be imagining the same hypothetical codebase. Yet we never bust out concrete code. It's funny.

But the outcome that you're lambasting so rudely (really? "terrible idea" when we aren't even looking at code?) is still often the best outcome.

Some rotting, bugless, duplicated code is some of the easiest code to work with. It's the code you wish you had when you're debugging the complicated failing abstraction that GP wanted to avoid. The most damning thing you yourself could say about it is that it was taking up space.

In fact, you seem to be making the exact reverse argument of GP: that some duplicated, unabstracted, bugless code poses such a risk ("rot") that it's a "terrible idea" to not immediately merge it into one frankenabstraction.

When this happens in an argument, usually you both are imagining an absurd extreme that's opposite of the other's chosen extreme. And you actually are in agreement, as you'd both go "oh well yeah, if you go to that extreme, then I'd definitely agree with you."