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.
Ignoring for a second they actually already are indeed, it doesn’t matter because the cost of rewriting the mess drops by an order of magnitude with each frontier model release. You won’t need good code because you’ll be throwing everything away all the time.