I've yet to understand this argument. If you replace a brown turd with a yellowish turd, it'll still be a turd.

In everyday life I am a plodding and practical programmer who has learned the hard way that any working code base has numerous “fences” in the Chesterton sense.

I think, though, that for small systems and small parts of systems LLMs do move the repair-replace line in the replace direction, especially if the tests are good.